Quote Originally Posted by Ross
UPDATE
There is a spark knock when the throttle is snapped open as well.
What are your automatic M50s like off idle when the throttle is snapped open from idle??
Spark knock with no chip and good fuel? Sounds like crank sensor signal or engine computer freaking out.? Or is the crank sensor in the wrong position for some reason (road crap knocking it around)? Seems a reach... After typing the below, I got to wondering if you have carbon build up in the combustion chambers that might require some Seafoam-type action? That would explain the spark knock on throttle snaps.

Didn't I read on here the other week about somebody cursing their coolant temp sensor for causing a driveability problem like yours. They did the very same things you have done and were kicking themselves after it all came down to a sub $20 part.

My 95 525 auto responds instantly from idle snaps, but not as strongly as when snapped at higher rpm's.

I would love to see the vacuum and fuel pressure gauges during your stumbles. That might be very illuminating.

Brian