BMW had a recall about cracked throttle cable ferrules. Many M42s I've seen have a cracked ferrule at the throttle cable mounting plate. Sometimes they twist out of alignment and can bind.
BMW has a little spring clip that your local dealer's parts counter should know about. It's an OEM band-aid for the M42 & M50 motors. I couldn't find a part number or TSB to back it up though.
Hey Dave, I have been experimenting with my car and I think the issue is throttle related. It still only comes on when I am idling after driving a bit, going down hill in neutral, or not giving it any gas while coasting. But it goes off as soon as I give it gas or bring it past 1500 at idle. Another issue that could relate is when I decelerate and put it in nuetral, the idle will go down to about 1000-1100 and stick there. But when I give it gas and bring it past 1500, it will go back down to 800 or so. Hope that makes sense, I really don't know what else to do.
