what could cause car to lose fire?

i have a 1995 mustang v6 car i bought, it had already been swapped to a 5.0, oil pump locked up on the motor that came in the car . after swapping the car it fired up and ran twice and on the second run it just kind of sputtered out and died now it will not fire at all, replaced ignition coil, ignition control module, and distributor and still having the problem, after replacing everything it fired up for approx 30 seconds and died...