1985 745t

Car starts and idles fine; almost always starts on the first crank of the starter motor, has plenty of power, and is generally fairly quiet. Car has had all its maintenance with new filters, belts, plugs, adjustements, etc.

The problem occurs when you first get under way from a cold start. When I put it in gear and let out the clutch the car stalls out a little bit and stumbles. It rarely stalls completely and just seems to have trouble with the initial load of the vehicle moving forward. The problem seems to be more pronounced when the car has been sitting in the sun for a hot soak, but its noticeable all the time.

I've posted on this problem a few times, but no one has yet come up with an answer that works. Below are some of the ideas and reasons they don't really apply.

1) Fuel Check Valve
If the check valve was faulty or open and letting fuel drop from the rail the car shouldn't start as quickly as it does. If it was just kinda bad it should still not idle as perfectly as it does.

2) Leaking Injector
If the injector were leaking I would expect to see some evidence on the plugs, either in the form of a wet plug before a cold start in the morning or telltale coloration of a rich condition on said plug. All plugs check out perfectly and are dry as a bone.

3) Vacuum or Air Leak
All hoses, including vacuum hoses, pressure side turbo hoses, and amm hoses check out perfectly. No holes, no leaks, vacuum hoses were replaced not to long ago, etc.

4) ECU Eprom update
Someone mentioned these cars can have problems with winter fuel mixtures if they don't have an updated eprom. This problem surfaced in the winter, but its now the middle of summer and still going strong. Should be gone by now if that was the case.

I know other people have experienced this problem as well, but no one seems to have been able to track it down successfully. Any help or insight is greatly appreciated.

Thanks,
Rick