My wife has a 96 GT Automatic with no mods except a K&N Filter with the silencer removed, Mac O/R H-pipe and a Flowmaster American Thunder cat-back. When I am in overdrive, and I accelerate lightly, the car surges like it is trying to downshift, but I am not accelerating nearly enough for a downshift. The tranny was rebuilt about 20,000 miles ago (June '02) and a shift kit was installed. I have cleaned the MAF, new plugs, wires, fuel filter, cleaned the air filter, and it still won't go away...any suggestions?