I have a 92 500E with 25,000 miles on it. It has had this problem for a while and no one can figure out the cause. WHen the car sits for a few days, 3 or more days, it starts normally but then hesitates and is jerky under accleration for 20 mins or so. Sometimes the jerkyness will totally dissapear for a few seconds and then return. While the car is hesitating it probably has about 30% of its power. After the car runs for a while this clears up. Lately, it even idles rough during this period. Any ideas?

Shawn