I have a 1996 k1500 with new 383 vortec engine. Trucks starts up, runs but under throttle throws p0300 code. After it warms up 5 to 8 minutes, it starts to sputter and die. It does this consistantly after it warms up and usually around 1500 + RPM. New fuel pump that has key on 60-66 psi. Runs 56-57psi idle and will raise sightly when I give throttle. After the truck dies, it will bleed off from 57psi of fuel pressure to about 45-50psi within a minute? Fuel Psi regulator? The previous owner has put on the upgraded MPFI unit. New spark plugs, new wires, new coil, pickup coil, new distributor, new EGR, new MAF, MAP and new intake gaskets. Any suggestions. I have tried another coil, pickup and still same problem, same P0300 code thrown...