Hi, If any one can help with this most irritating problem it will be most appriciated. My 1983 380sec surges from 600-1000rpms once it heats up every couple of days.Some days it runs fine. I recently bought the car and it had some hesitation.My certified MB mechanic said the fuel frequency valve was disconnected. He cleaned fuel dist. set the lambda,new plugs. The car ran fine then the surge returned. He then adjusted fuel pressure. The The car ran fine then the surge came back after a few days. He then replaced O2 sensor readjusted lamda through hole in air cleaner. On the way home from the shop it surged for about 5 mins went away for a few days and returned again!