car in question is a 91 GT automatic. it runs and drives good except for when i try to get on it. it doesnt kick down when i step on it, it just back fires through the intake and sputters... if i drive it normal or slowly press the throttle i can get it going good but on the freeway when i try to get it to kick down or when i step on it hard from a stop it just falls on its face. so far i have changed the plugs, wires, tfi module, fuel filter, put the stock injectors in (came with 24#), the MAF is stock. I just put a coil from my other mustang. i checked the fuel pressure and it was in the 40's. im thinking it is getting too much fuel when i step on it... in my mind all i can think of is the fuel pressure regulator but i havent changed one before and i havent had one go bad so i dont know exactly what it does... but if it is bad and somehow allows too much fuel to go to the injectors than that is what it feels like... i am going to change the cap and rotor tomorrow just for fun although they both look ok... any other imput, suggestions or questions to help find out what is wrong is appreciated! thanks!