Missing at 4500

like the title says my car is missing horribly at 4500 up to 6000. within the past few months i've added tfs h/c/i, 70mm tb, 80mm mass air, walbro 190 fuel pump, kirban afpr, 24lb injectors, msd blaster coil, 9mm plug wires, new cap and rotor. when i start the car and unplug the vacuum line to afpr we set it at 42 lbs then when i plug it in it drops to around 35 at idle. i take the car out warm up the engine come back and vacuum off pressure drops to like 35 and around 30 vacuum on. i've checked the voltage coming into the pump and made sure my inertia switch also had full voltage. any ideas as to why the pressure will remain constant and why the car would miss so bad?
 
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