Your car has a throttle actuator, and it could be causing your problem.

Another item could be the mass air meter.

You should also check for vacum leaks. There is a plastic vauum line at the front of the engine going to the Air Pump switch-over-valve. They commonly crack from heat and this can cause a rough idle.

Have you replaced the spark plugs and the three resistor boots under each coil?

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".