i have a 1997 CHEVY CAMERO 3.8L, auto, when the car get hot the car startes to act funny, the Rpm starts bouncing around, (note the engine is ideling funny also when this happens , so its not just the cluster) this only happend this summer, it never happend in the winter. i took it to the GM dealer and they couldnt diagnose it, they were leanning toward the ignition coil, but werent sure, so i took it back from them and i replaced a ignition coils (all 3) with a known good one(all 3) still the same problem.... recently i replaced the catylitic converter because it was plugged, and the car kind of runs rich.. so i am totally lost here not to sure whats up with my car.... did anyone have a similair problem? or does anyone have a clue what it could be? the car has no falut codes... and this problem is intermitten. If anyone can help that would be great, thanx

 

Try replacing the 02 sensors . When you rev the car have someone stand behind to see if you have and excessive carbon smoke coming out of your tailpipes...

 

if its running rich make sure all the air intake pieces are air tight. make sure the air filter isn't dirty too. as far as it jumping around when hot change out the coolant, maybe something somewhere is clogged in the cooling system.

 

Pull the wires from the MAF sensor & see how it runs when warm. This will cause the MIL light to go on, but do not worry about it for now. By pulling the wires you force the car to stay in the open loop mode. If the car runs better in this condition, it indicates that there is a bad sensor, and not necessarily the MAF sensor.