Hi, I have had the same problem for the past year. I have a 2000 BMW 328ci and Once in a while my check engine light will come on and I will notice that my car has erratic idling. I have a code reader and every time i do a diagnostic check it always says the same thing...Cam shaft sensor(intake side). the problem is I have replaced this sensor two times. I have even changed the cam shaft sensor in the exhaust side. Also after i reset the codes it will run fine until the next time i try to start the car. It will start but it takes longer to start then normal. It will also have hesitation while accelerating and at stop lights have erratic idling. I was told by Auto zone that it could be the camshaft sensor or the timing chain..Obviously its not the sensor but could it be the timing chain? or is it some thing else?.....Someone PLease Help!