OK... I've owned a 90 Mustang GT for about a year now, and about halfway though my ownership i've noticed a irritating problem where the car has a tendancy to rev even when I'm off the accelerator! It's an on and off problem which makes it especially anoying because sometimes I can drive the car for an hour with no problem but it might occur if I start it the next day and will continue. Ussually I know the problem is occuring after I start the car and the idle switches to a lift reving without any involvement from me (like, maybe from idle up to 1500rpm's or so-over and over again). But I have had it go up to over 2000rpm's and stay there while I was at a stop light. Most commonly though, it sometimes revs while i'm shifting which makes smooth shifts nearly impossible and I know it's not very good for the transmission. The car has all the common bolt-ons: shorty headers, Flowmasters, underdrive pulleys, k and n filter. But I think the problem might have something to do with the aftermarket MAF meter, which is a 76mm C and L. I haven't done any mods to the car while owning it that might have thrown someting off.
But what should I do? Any good advice would be really appreciated!