I am fusturated with the cruise control on my 1992 300D 2.5 turbo. The cruise worked fine on my long 15 hr drive and the way back, but then it started creating problems. When I looked under the hood, the linkager was loose and the ball/socket joint would not hold together, so my mechanic replaced the linkage with another one. Then, as the problem persisted after that (??) my mechanic then replaced the actuator, which turned out to not be the problem, and some sort of an amp or switch behind the dash he replaced as well to be on the safe side. The last thing I can think of is the computer under the driver's side dash by the knee. Here are the current symptoms: The car's cruise control stick works (after all of these replacements),it accelerates but the cruise does not set, it holds for about 3-5 seconds and then decelerates and does not hold the cruise. The fuse is fine, the brake lights all work....is it the computer under the dash? Please help) I am confused.