Benzmac mentioned driveshaft vibration. what you are describing sounds more like what he suggested. May be a joint, flex coupler, or support bearing. Your description would also suggest something in the suspension. sounds like the engine can be ruled out. I really think you need to have a compentent tech look this one over. You may have more than one problem. Whatever it is, you had better get it figured out before throwing any more money at it. Do you get any shaking or vibration thru the steering wheel?? Coming and going could indicate a flex disc about to head south.
1987 BMW 325
[This message has been edited by jeffsr (edited 06-21-2000).]