Check engine light, code said replace cam sensor. Did that. Now when rpm hits 3500 it cuts out and drops to 750 rpm and starts firing again. If left idling runs no problems. Will run sustained rpms until it reaches the top rpm mentioned earlier. If throttle is held to maintain top rpms mentioned it runs thru top to low rpm cycle with out stalling complelely. No warning lights or active codes. When at temp, cuts at 2800 and catches at 750
Sounds suspiciously like a Mass Air Flow (MAF) sensor or Throttle Position Sensor (TPS) is either unhooked, fouled, or in need of replacement. In my experience, that's generally what causes the symptoms you have described, although I do admit that BMW's aren't my specialty. Either way, that's what I'd check first.
also be aware that the circuit for cam sensor is inline of the one for crank sensor and a faulty crank sensor can throw a cam fault.
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