I have a derivability question. 80% of the time, when I let up on the gas, I feel a harsh jolt and can't tell where it coming from. I have replaced tran. mounts (5 speed), so I can rule those out. It doesn't do it all the time, only when I let up on the gas suddenly. Almost as if there's too much slop in the drive line. Had by local mech. check it out and he couldn't find anything wrong or worn in the drive train. Any suggestions? Richard V '92 535i 5 speed 96k