My C240 when warmed up has a hesitation at low speeds or in a pull but will stop momentarily if I let off or press down more on the accelerator. Sometimes when it hesitates I hear a slight roar from under the car. I have already replaced the throttle actuator and this did not help. Wonder if it is the accelerator peddle assembly?

Your best bet , take your vehicle to a qualified repair shop that has a professional scan tool an service repair info . So it can be diagnosed correctly . The Stop lamp switch is not a old school conventional type . Has three wires , five volt ref. voltage from the BCM ,
Stop Lamps
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM). Ground for the right rear stop lamp and CHMSL is applied at G402. Ground for the left rear stop lamp is applied at G400. The stop lamps on this vehicle will not illuminate unless the ignition is in the accessory, run, or crank positions. When the ignition is in the OFF position the stop lamps will not illuminate when the brake pedal is applied.

Checking for DTC's - diagnostic trouble code's in the BCM would be my first diagnostic step , not guessing an replacing parts .

DTC B3903 02: Stop Lamp Relay Circuit Short to Ground
DTC B3903 05: Stop Lamp Relay Circuit Open or Short to Voltage

DTC C0277 06: Brake Pedal Position Sensor Circuit Short to Ground or Open
DTC C0277 07 : Brake Pedal Position Sensor Circuit Voltage Above Threshold
DTC C0277 09 : Brake Pedal Position Sensor Circuit Rate of Change Above Threshold

DTC C0278 00: Brake Pedal Position Sensor Not Calibrated

DTC C0870 03 : Device Voltage Reference Output 1 Circuit Voltage Below Threshold
DTC C0870 07 : Device Voltage Reference Output 1 Circuit Voltage Above Threshold
As you can see a number of DTC'S can be set , so do yourself a favor an let a qualified technician check it

Circuit/System Description
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM). The stop lamps will not operate unless the ignition is in the ON position.

DTC P0572 : Brake Switch Circuit 1 Low Voltage
DTC P0573 : Brake Switch Circuit 1 High Voltage

It's hard to fix something when you don't have a clue how it works . The CC is also a controlled function of the BCM .
The BCM monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the ECM via the GMLAN serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine and the desired vehicle speed. The ECM uses the TAC motor in order to maintain the vehicle speed. For further review of the TAC system, refer to Throttle Actuator Control (TAC) System Description for the 2.0L engine or to Throttle Actuator Control (TAC) System Description for the 2.4L engine. Ignition voltage is supplied to the cruise control switch from the 2-amp CRUISE fuse located in the integrated BCM fuse block. The cruise control switches are located on the steering wheel. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM detects a specific voltage value that is associated with any cruise control function switch being activated. When the normally open cruise control on/off switch is turned ON, the switch closes and the BCM detects a predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the On/Off switch is active. Similarly, when the + RES switch or the - SET switch are pressed, the BCM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. To engage the cruise control system, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise On/Off switch ON and momentarily press the - SET switch. The ECM will engage the cruise control system and record the vehicle speed. The ECM sends a GMLAN serial data message via the BCM to the driver information center (DIC) in order to display the CRUISE ENGAGED message. The - SET switch or the + RES switch will remain inactive when the BCM has not received the predetermined voltage signal from the On/Off switch. Pressing the accelerator pedal, while the cruise control system is engaged, will allow the driver to override the cruise control system in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the - SET switch and the + RES switch. When the cruise control system is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the cruise control system. When the - SET switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the cruise control system is engaged, momentarily pressing the - SET switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the - SET is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing and holding the + RES switch, when the cruise control system is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the + RES switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the cruise control system is engaged, momentarily pressing the + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily pressing the + RES switch after the cruise control system has been disengaged by pressing the brake pedal, will recall the previous set vehicle speed that is recorded in the ECM.

Check timing of the engine is right using an engine timing light. Make sure the timing belt or chain isn't worn or slack. The head gasket could also have gone and may need replacing.

Huh? Doesn't it start out from a stop in first gear? Flush what, what belts?

When you press the gas pedal all the way down, does the engine speed up quite a bit, or stay at a very low RPM?

Does the engine miss? When did you last do a tune up? How many miles on the van? How does it run once you have reached high speeds? Any other symptoms?

Not much information for us to go on.

Tune up all.

transmission issue or possible even transfer case? i had low transfer case fluid and that happened and there was metal screeching sound. my car hesitated then grinded down to stop. had to put more oil in the T-case. but then yours might just be transmission issues possibly?

ENGINE HESITATES WHILE ACCELERATION
LOSS OF ACCELERATION

It can be fuel pressure issue or it's the problem with accelerator pedal or its clogged filters causing there.
There are many other possibilities. I suggest you to go through the list of help links mentioned below, these will help you to confirm where the actual fault lies: -------
Jerks and Hesitates During Acceleration?
http://technoanswers.blogspot.in/2012/07/2004-dodge-town-country-jerks-and.html
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Loss of acceleration?
http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html
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Headlights flickering and car hesitates to start?
http://howtobyme.blogspot.in/2012/02/headlights-flickering-and-car-hesitates.html
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How exactly the Vehicles Accelerator Cable works?
http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-cable.html
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How exactly Vehicles Accelerator Pump Diaphragm Works?
http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-pump.html
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2000 Toyota Avalon: Engine Lean Codes and Knock Sound on Acceleration?
http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-engine-lean-codes.html
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2004 Toyota Avensis: Acceleration And Deceleration makes noise on Front End?
http://whatisbyme.blogspot.in/2012/05/2004-toyota-avensis-acceleration-and.html
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Wheel hop under hard acceleration?
http://technoanswers.blogspot.in/2012/04/wheel-hop-under-hard-acceleration.html
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2009 Chevy impala accelerator pedal sensor?
http://technoanswers.blogspot.in/2012/02/2009-chevy-impala-accelerator-pedal.html
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Nissan Pathfinder stalls and bucks on Acceleration?
http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html
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Acceleration lag problem?
http://repairhelpcenter.blogspot.com/2012/01/acceleration-lag-problem.html
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These details will help.
Thanks.

Air filter and dirty throttle body.

i had this similar problem on my kia optima. Does it hesitate when it switches gears when accelerating if so. The problem is the fuel pump. i had to replace mine and that solved my problem.

Sounds like a malfunctioning egr system. Too much egr gasses at once will lean out the air fuel mixture and cause hesitation in an engine. Just my 2 cents.

hi,

sounds like a vacuum leak, injectors clogged, bad plugs, plug wires or maybe low tranny fluid or combo one all, have it dynoed to save yourself some money of course.

good luck

J