The '92 300e I bought a couple months ago had a strange vibration that was most noticeable when the car was in drive and stopped at a traffic light. After reading some posts here I suspected the motor mounts might be the cause. On inspection, one motor mount seemed to be about 1/4" more compressed than the other one, even though there was no leakage or obvious signs that it might be bad.

I took a chance and ordered a new motor mount from Fastlane and installed it tonight (20 minute job). The car idles so smooth and vibration-free now I have to look at the tach to make sure it is running.

Another problem solved, thanks to Shop Forum.