Okay, I've have some cruise control surge at highway speed, and the speedometer has had intermittent flutter with or without cruise control engaged. With the cruise control engaged it surged when the needle started to flutter. There was a definite correlation.

Last year when I was undernearth replacing the clutch slave cylinder I removed the speedo cable from the transmission, and it turned smoothly, so I reinstalled it. Both the cable and speedometer head were replaced on warranty circa 1991.

For some unknown reason, the problem has not reoccurred, but I barely used the cruise control in the last year.

Suggest you look at the cruise control service info on the braingears site. Be sure to include "technical modifications" and "program repairs". I recall from skimming it that there was some information about adjusting the link from the actuator to the throttle linkage as a cure for surge problems.

Duke