Where is EGR valve on 1997 Mercury Mystique 2.0 - 4cyl.

Look at some of these videos, especially the ones from Scotty Kilmer. It may need replacing.

https://www.google.com/search?q=cleaned+mass+air+flow+sensor

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Check the egr valve also. If the check engine light is on go to a O'Reilly auto or any part store to have them check the codes.

What you would need to do is find out which part is making the problem. By this, I mean the electric solenoids which supply Vacuum to the valve or the EGR valve itself or the EGR ports feeding the exhaust to be recirculated.

Free "check engine light" tests are available at major parts stores like Autozone.

You can test the EGR diaphragm by using Vacuum or by pushing the diaphragm open and putting your finger over the vacuum opening and sealing it off.

You may also have soot in the EGR valve prevent it from closing. Remove and clean the EGR.

Check your mass air flow sensor (maf). It can be cleaned with brake cleaner or MAF cleaner.

A few things ,97;tune up, fuel filter,air filter,clan throttle body,put in tank some fuel injection cleaner good one not cheap.

Check the purge canister.

is the check engine light on

Wow you change everything, TPS was right thing to do and so is the Idle air control,and MAF and EGR, fuel pressure, So it idles high then some one tried to defeat the stall in gear? Even if there is a vacuum leak creating high idle it shouldnt stall in gear, , What color is the transmission fluid? when in gear in drive step on the acelerator pedal to maintain idle to prevent car from stalling. Just enough to maintain let say 1100RPM. Is there a vibration? I mean a torque convertor vibration. Torque convertor stall are common an GM and Nissan,very rare do I ever see it on Ford. I really belive the IAC is not getting power and is just been adjusted manually, cause I know its not the transmission, At idle in gear pull the plug on the idle Air control does it change in idle setting? If it doesnt change in Idle setting the adjustment that was use to control the setting lower the idle to its normal setting. Plug the idle air control in then.The idle air should change the setting. If it doesnt its not getting the signal it should.

P0401- Exhaust Gas Recirculation Flow Insufficient Dectected
Possible causes - Harness or connectors (EGR volume control valve circuit is open or shorted.)
- EGR volume control valve stuck closed
- EGR volume control solenoid valve
- Dead (Weak) battery
- EGR passage clogged
- Exhaust gas leaks Possible solution - Clean EGR Valve
- Repair EGR harness or connector
- Replaced EGR volume control solenoid valve
- Replaced EGR volume control valve
Code P0171- Fuel Injection System Too Lean Bank 1 Possible causes - Intake air leaks
- Front Heated oxygen sensor may be faulty
- Injectors may be faulty
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Mass air flow sensor may be faulty
- Incorrect PCV hose connection Possible solution Dirty air filter of faulty air flow sensor are common causes of the problem P0174- Fuel Injection System Too Lean Bank 2 Possible causes - Intake air leaks
- Front Heated oxygen sensor may be faulty
- Injectors may be faulty
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Mass air flow sensor may be faulty
- Incorrect PCV hose connection Possible solution Dirty air filter of faulty air flow sensor are common causes of the problem.

i hav a 2003 pt cruiser 2.2 crd touring it wont go over 3000 revs engine light cums on. error code p0243 i hav replaced wastegate solenoids cleaned egr valve cud it be the mass air flow sensor that has a problem thanx