1995 Mercury Cougar • V8 2WD Automatic • 53 miles

I had a bad misfire for about 2 months, I changed the plug wires and that fixed it.

Now I have a problem with hesitation on acceleration as well as rpm dropping down to 1k rpms while the engine is under load. Note: this only happens when the car is warm, when it is cold it is fine.

Also the cars idle after its warmed up stumbles a little bit.

Things I've Changed:
fuel filter
spark plug
spark plug wires
air filter

Any idea what could cause this?

January 31, 2011.

Could be caused by one of the following below

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard it and keep testing.

Jan 31, 2011.