1st89FOXBODYGT

I recently just bought an 89 mustang that had gt40 heads and intake, car tan when I bought it but had blown head gaskets, put.new ones on and ran great for 2 days then acked like it ran out of gas, still have 3/4 of a tank, I replace fuel filter, injectors, maf sensor fuel regulator, distributor, ignition coil, iac valve, tps sensor, u name I have done it, still not running, do I need to adjust the valves, could that be why it isnt running, fuel pump is.still pushing out fuel pressure but it stays on constantly even with the car not running, but in on position