I've been noticing that my 83 300SD is starting to speed up and slowdown when the cruise is on. When I go uphill, everything is fine. But when I am on flat ground the car surges constantly, and if I put my foot lightly on the accelerator I can feel the cruise actuator really pumping. I mean the accelerator probably moves up and down probably faster than once every second.

Is this the cruise control amp starting to burn out?