Just purchased a 1984 300CD w/150k for my daily 200 mile work commute. The cruise works but is so annoying, I don't use it. It accelerates over the set speed, then adjusts itself by slowing down below the set speed, then does it all over again (5-10 second cycles). The ball and socket connectors on almost all of the throttle linkeages are loose/worn. Is this a likely cause or is the control unit the most likely culprit?