I have a 1992 auto 525i which began lunging or surging with the cruise control set about two years ago. At first it was only once or twice an hour and they were weak surges. Lately the surges and become severe lunges about twice a minute in hot weather.
The car will jump forward for a spit second and then let off only to repeat itself later. It is worse in hot humid weather. I live in North Carolina, USA where the summers can be very hot. I also have a problem with surging under acceleration without cruise control on.
Does anyone have any thoughts regarding a solution....and/or a cause?