I have a 1990 5.0 with a powerdyne supercharger (currently discontinued) and I when I accerate hard it hessitates or bucks at around 3,000 RPMs know matter what the boost controller is set to or timing. I have a Walbro 255 lph fuel pump, vortec FMU, MSD boost controller, and Kirban adjustable fuel pressure regulator. Engine is stock minus Ford Racing shorty headers, 2.5 full exhaust X Pipe with flowmaster 40s. At first I though maybe its due to the 15lb. pulley but then I tried with the belt off the supercharger/ Just to see if it was getting too much air for the stock MAF and and injectors no change. I tried with and without the FMU and at every adjustable psi I could think of with the Kirban fuel pressure regulator and am now out of ideas. I plan to get 30lb injectors and a 73mm MAF with 30lb sampling tube but I've know of other mustangs the can run with stock injectors but I am out of options please hook me up with some input. Thanks all