My mach has been studdering when you give it any more gas than normal street driving, its very obviouse between 2000-3000 rpms. No check engine light and I thought it was the air filter so I cleened that (k&n filter stock air intake). I then replaced the fuel filter and that seem to help a little bit too. But it still studders, the only mods i have are long tubes, o/r mid pipe and catback...any sugestion? O yah the check engine light has not come on.