89f15089

I have an 89 4.9 5spd. It started randomly sputterin every once in a while just once or twice, then it started more and more frequently and worse. Then it got to the point it wouldn't even start. I have replaced the in tank pump, high pressure pump, fuel filter, fuel pressure regulator, TPS, ECM, ICM, coil, plug wires, plugs, idle air control valve, and cleaned all the contacts on the inside of the cap and the end of the rotor button, today I replaced my intank pump again cuz it burnt up. After I did that i primed the lines back up and it started up ran fine revved up good for about 3mins, the. It sputtered and died. I restarted it and had to tap the throttle and keep it above 1000 to keep it from diein, as soon as I stopped fetherin the throttle it sputters and dies and it won't rev over 2500. Any ideas on what it could be?