Sounds like you may have the same problem as these guys.
You also didn't mention anything about changing the fuel filter. It would probably be a good idea if you haven't. Who knows, maybe you'll be the first person to have your problem resolved by putting in a new filter. Lol
08 GT 5spd
Spectra CAI, Comp Cam Detroit Rockers, Kooks headers w/catted H-pipe, Revolution Automotive dyno tuned, FB430 race mufflers, 3.55s, JLT catch can, BMR Lca's and relo brackets. Prothane motor mounts and sway bar bushings.
20% tint, smoked markers and tail lights w/sequentials. Clear front signal covers, series 3 chin spoiler.