If it only idles poor when cold then start at the main bleed valve (stepper motor I think on this unit). Unit should be fully closed when warm. May be just the setting of this valve for a cold start. Take the feed off to this unit valve should fully open giving a high (1500 rpm)idle speed. This proves unit is working to some degree.

Ian

My M5 3.8 idles poor until it reaches 70 degree Celsius.
We checked the ignition coils, valve play, idle control valves and the injectors.
What else can we check ?

Niki

Crank speed/reference pick-up
Leak-down or compression.
Spark plugs.
Vacuum leak at throttle body(check vacuum hoses and port caps).
False air leak ahead of throttle bodies.