Guys, I just picked up my car from a very good independent shop here in Walnut Creek (IndependentMercedes.net). I told the shop owner (Bill) about vibrations and rough idle problem that's been bugging me for years and he suggested that the transmission mount could be of a problem. Parts and labor for changing it out was $70 and wow what a difference did it make.

There is no more vibration while idleing anymore. The vibration at highway speed 50-70mph is gone. The mount's life span is only around 3 years. So if you have a car as old as mine... get it changed.