BMW Repair: E46 almost stalling, new sensor, e46 coupe

Question
Hi. I recently bought an E46 coupe, 2.2ltr. Within 1 day the camp position sensor went so the engine kept stalling. I had it replaced and it stalls no more~! - except that when I put the clutch in the revs drop to around 500 and it needs to catch itself and bring the revs back to around 600 for smooth idling. Since the new sensor it also behaves strangely and sometimes (clutch in) drop to 1000, hovers for a while, then drops to 500, then up to 600. Do I need a new map in the ECU or something? Any help gratefully received. Roy

Answer
Roy, sounds like the idle control valve maybe getting sticky. Remove it and clean it or replace if you cant hear the door swinging freely when you shake it in hand. Also check the intake boot that feeds the idle valve for tears. Anyway that is where I would look first.
-Evan