2011 GT started sputtering at around 3k RPM. Doesn’t matter what gear you’re in. Changed plugs, cleaned MASF and throttle body. Fuel pump seems fine. No misfire codes pulled. Mods are K&N CAI, BBK cat-less long tubes, X-Pipe, Roush mufflers, Lund Tune. Anyone help would be great. Car is not driveable due to sputtering.

 

Did you pull any other codes?
Try changing the fuel filter. You might also want to inspect the fuel pump filter sock in case it's clogged with dirt.