RPM jumps on idle
 

hi, people i m having a funny problem in my car when on idle the rpm jumps a little and even the daeler failed to get to the cause they charged me almost 400 dollars they said it was the supressor switch that they changed 2 of them and they said they changed the spark plugs too but even after that the problem is still there any idea would might help me a bit i have a 1993 400e with 35,000 miles
thanks
mani

It could be any number of things. Check for a vacuum leak. Do you hear any whistling?

no i dotn hear any kind of whistling its just when car is idle or stopped at a stop sign it would do that other than i dotn feel anything while its running ray catena in new jersey tried to fix the problem by saying that it s the supressor switch and they replaced it but it seems like they failed in order to solve my prolem i m thinking of taking to another dealer over here next week hope they can fix this
thanks for ur reply though
mani

whistling noise
 

I recently had a claning noise by the alternator and was told it was the air pump pulley going out...I have taking my car in this week for repair but now I hear a whistling noise when I press on the gas pedal....it only happens when the car is not quite warm yet.

Any thoughts?