Check your ETA which is under the Mass Air Flow Meter, for degrading wires, could also be have lots of Carbon build up around the endges of the "flap".

I know on my '92 400SE, I cleaned up the edges with brake cleaner, and it ran like new, I was having rough idling. You have to remove the MAF to clean it right and without damaging the MAF.

Also have your computer scanned, mine doesn't have the "Check Engine" light, and when I had it scanned there were a few codes that corrected my problems.

Regards.