My 1994 Cadillac Concourse 4.6 runs fine when cold, but when it warms up, the idle goes haywire. It jumps up and down and will die at stop lights. Starts right back up and drives fine. I can feel the pedal move to try and adjust for the idle problem but it doesnt help. Any suggestions?

 

The reason it is ok when cold is because it is being fed a bit more gasoline, like the old fast idle on a carb.

I'd suggest starting with the plugs and wires and see how that works out. Don't get cheap wires either. I always use AC Delco parts on my Deville but it's up to you. I think they will make a difference. You should also change the fuel filter if you can't remember when you did it last and double check the air filter. When you have the wires off check the coils, make sure posts are good and clean. Let us know what happens.