hi,

looks like i have a fairly similar situation with the rough idle. happens only when car is hot, cold engine/starting is fine. when hot (80 to 100F), the idle speed in gear drops to 500rpm. have changed distributor rotor, cap, plugs, thermostat, coolant, and coolant temp sensor (since a couple of mechanics told me the engine maybe running hot.) all these things didn't really help. would appreciate your input.......could it be the ignition wire set or gas filter? the car's got 139K

when i drive, the car has plenty of pep and drives real smooth and well.

i test drove a (certified pre-owned) 94 C280 today at a mercedes dealership and that car had the same problem.

i am wondering if this is a wide-spread problem, and the possible causes.

also, any pointers on what the temp range should be - how can i tell if the engine is running hot and why?

Many thanks!