I searched threads with idle problems trying to identify my idle problem, which was different than yours.

What I found over and over again is that the throttle actuator is a common failure part. When the throttle actuator goes out, the cruise control goes with it. The fact that your cruise control is not working along with a bad idle is not a good sign.

Hopefully it's something else.

This would not be good news as the throttle actuator is about $1,000.

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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".