Rough idle when hot +
 

My '91 is running OK for a few minutes after a cold start, after that it's pretty crappy: rough idle and uneven rpm even on level road. It feels like the engine is controlled by a governor that keeps it from achieving a smooth run. Hard to descibe but, even when doing 60-70MPH, I feel it pulling back on the RPM like SHE'S oscillating up and down. Ive recently replaced cap, rotor wire and plugs and, just yesterday, the fuel filter (that was so bad I could not blow through it).
Any suggestion as to what I may look at next would be greatly appreciated.

Thanks for your read and regards,

Pat

RE: Rough idle when hot +
 

whens the last time you've replaced the o2 sensor?

RE: Rough idle when hot +
 

My '93 is exhibiting similar characteristics with a rather rough idle. Also, if I floor it, there is a large cloud of black soot that is emitted from the exhaust pipes. In addition, my Service Engine Soon light comes on sporadically so all of this points to the O2 Sensor. I am planning on taking it in to the shop Friday to get this resolved. I would venture to guess your problem is also O2 related. Good luck.

RE: Rough idle when hot +
 

Are you getting a "Check Engine" light? Might need to short together the 2 pins on the diagnostic connector to see if any codes are stored. The 2 pins in the upper right hand side of the connector and turn key on and watch CE light.

RE: Rough idle when hot +
 

A faulty temp sensor, fuel pressure regulator, injector, ECM, and 02 sensor are also possible. A check engine light on is always worth checking out but it may not be on for injector, fuel pressure too high/too low or an ECM problem. This is where your converter will end up getting plugged if you don't get the problem fixed! Cold start, the engine needs more fuel and if the temp sensor isn't reporting the correct coolant temp, the ECM will not correct the fuel mixture as it warms up. If the 02 sensor is not reporting correctly, same problem. Get a scanner hooked up to the car and a fuel pressure gauge. Bigal