It still sounds to me like you have the classic symptoms of a bad throttle actuator.

Bekman technologies in North Carolina rebuilds them.

Many forum members have gone this route.

Try the search function.

JimF has been particularly helpful. Read this thread:

http://www.peachparts.com/shopforum/showthread.php?t=112493&highlight=throttle

__________________
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".