My 1992 300ce 126k miles has a cruise control problem. When I first got the car at 98k miles it worked, then it died out slowly slowly. When you press the acceleration it accelerates for 2 to 5 seconds the cuts off, when the deceleration is pressed it accelerates for 2 to 5 seconds then cuts off, the resume doesn't work at all until you play with the acceleration which then nudges the car forward, basically accelerating on and off a few times in a matter of 2 seconds.

Its a bit complicated, I have searched HI and LOW and found nothing.
WHAT COULD BE WRONG?