I am also experiencing erratic surges when cruise control is engaged. An earlier post recommended checking brakelight bulbs, which could affect the cruise control performance. Brakelight bulbs seem ok, but I have since discovered that a hazard light must be out (as one indicator doesn't "blink" on the instrument panel).
Wouldn't the hazard bulb be the same as the brakelight bulb? Could this be affecting my cruise control? Thanks for any help.

ragtopper
380SL