It is using alot of fuel and is running poorly. It starts ghugging at higher RPMs. I gave it a tune up and changed the O2 sensors. Can you help me?

-scan for trouble codes -check air filter --map sensor [clean if dirty ] vacuum leak --cat converter--fuel filter

Have you checked for vacuum leaks? Poor idling when cold that gets better when the engine warms up, or at higher RPMs are symptoms of vacuum leaks. Check all hoses and connectors. If it's a manifold gasket, you will want to use a smoke machine (check when the engine is cold).

First check and see if you have spark at the sparkplug if you do then you need to check your fuel pressure.It sounds like to me that your fuel pump has went out to lunch.When you turn your ignition on try and listen for the fuel you should here it for the first 2 seconds you turn the switch on.

Or clogged fuel injectors . Do yourself a favor and save yourself the aggravation , take it to a qualified repair shop where they have the diagnostic tools an knowledge .

may want to have codes read on vehicle..it may be the O2 sensor causing the issue.

Try checking the Throttle Position Sensor!

I would change the air filter and clean the fine mesh covering the air flow control unit.
Make sure the connections are good as the sensor screen is tied to the O2 sensor. A new O2 sensor and dirty screen would give you poor fuel burning as the air fuel mix would be bad, and the O2 sensor would read the need for more fuel.......poor economy and running rough as it would not be clean burning.

It sounds like you're not getting enough fuel see if any of the fuel lines are leaking. Even the vent tube on the gas tank to filler neck,because that can cause poor fuel pressure.Another thing would be the stepper motor is going bad. And last check the cold start sensor right by the thermostat, the sensor with one wire going to it and is facing straight forward.

Might be going super simple here but from what you have said have you checked the wiring on your sensors? If you know that one works and you swap it and its not working its very possible the wires farther up are shorted or burned somewhere.

Did you reset the ECU after changing the sensor? If not you need to (procedure in 2nd pic below), that way the fuel trims are reset and the ECU can re-learn the Short term and Long term fuel trims. this could be the cause of the difference in MPGs.

An O2 sensor will have no effect on RPMs/MPH. the only thing i can think of that would effect this besides changing gear ratios, would be changing the overall diameter of your tires or possibly a slipping clutch.

Check the codes on the ECU. here is the procedure:

(CLICK PICTURES FOR FULL SIZE)