Well took a trip up to the boat in the M3 last weekend.
Just out of town my car started accelerating on the freeway after I let off the throttle. Turned off the car thinking it was a stuck throttle. It ran fine for a while but started to persist and was idling at about 3k. I disconnected the battery and it ran fine for about 2 hours. but, it was still low to drop rpm's. It happened once more on the nearly 4 hour trip but was fixed by disconnecting the battery. It happened one more time yesterday, but not as bad.
After some searching I thought it might be the the throttle position sensor or the accelerator pedal assembly. After some more searching I thought I'd try 8 bucks of MAF cleaner.
Took it apart. sprayed the shit out of. let it dry for about 5 minutes in the sun this afternoon (freakin hot out) put it back in, let it dry for a beer's worth of time. Fired her up, and she's running awesome. I didnt really have enough time to see if there was any horsepower gains, but it always pays to try the cheap fix first