ok im stuck now

[mustangmadman]

i got that plug and know how to time the car my big prob is i swapped the stock cam with a b cam...........it idles fine and mean as hell i get on it and it wants to go but it doens go..........it dies off at like 3500 to 4500 rpms..............firing order is fine and timing is fine....................just cant get it to run right while im driving................its not mashing springs or valves because the heads are ported and built gt40p...............i changed the fuel filter as well thinking it might be a fuel starvation problem.......i dont have MAF because its a speeddensity car.............