2006 GT with a studder when driving. It feels like back pressure build up, but not sure. I have JBA exhaust with Pypes off road x-pipe. No cats. I have had the car like this for the 8 years. Its just recently starting to do this. It only does it while driving. It isn't lacking in performance wise, just this annoying thing. Any ideas or help would be great!

 

Ruling out any recent mods or retunes, I'd have to consider what normal maintenance you may be behind on (fuel system cleaning, new fuel filter, TB cleaning, air filter replacement/cleaning, plugs, etc) and, after that, then begin looking at malfunctioning sensors.