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Mustang has bad hesitation off idle

Hey guys I’m new here to the site but I’ve got a good one for you all. 1985 coupe, 351 Windsor with wiring harness and computer off of a 1991 5.0. I’ve installed 47lb injectors pro-m mass meter calibrated for injectors 4” cold air pipe filter in fender. It has a Vic Jr intake with a 4 barrel progressive linkage throttle body. It has a 380 lph fuel pump msd ignition. Now the problem I’m having is car cold starts fine but touch accelerator it has a bad hesitation you have to play with the accelerator to get it to rev but now when it gets around 2500-3000 rpm lord have mercy it turns on up and i mean fast around 7200-7400 before i can get my foot up. Now once the engine is warm and you shut it off to restart it you have to crank it and hold accelerator to the floor I have gotten 20 plus years as a technician and about the same time in performance but this one has me stumped so if you have any idea about it please let me know