Anyone wanna help with a Mustang issue?

[decibels5]

Looking for all ideas and thoughts. I just bought a 94 mustang with a newly rebuilt 5.0 HO. Problem I am having is a HESITATION Problem, not to be mistaken for a miss. New plugs, wires, coil, cap and rotor. To better explain the problem it feels like the engine will not wind out. Kind of like something is holding it back. Of course it only does it when your driving, (under load). It will power stall quite easily, and seems to rev quite nice in park. Items I am worried about. catalytic converter, stall converter, egr, throttle body, mass air flow, am I getting enough fire to the plugs, transmission. Car runs, idles fine, and drives good. Just not where it should be in the power band. If you can rule any of these out or make some suggestions, I would appreciate it.

 

[NYC LS8]

Put a fuel pressure gauge on it and see if it's holding pressure when you get on it.

 

[decibels5]

Found out it was the Mass Air Flow sensor. Dam I love this POS. So far. it now has new engine, (from previous owner), accel wires, msd coil, new plugs, new cap, rotor, new radiator, new hoses. new top, new floor mats, new seat covers. flowmaster exhaust (cut the pipes off today) Next major issues are fix electronics to convertible top, get new heater core and metal heater tubes that run along the intake. Wheels and tires will be as soon as I get a good used set. And the last thing will probably be a rebuilt tranny with shift kit and 2000+ stall. oh yeah, think I need an alternator.