I have replaced the computer under passenger seat (corroded terminal) I have replaced the injectors, plugs, plug wires, fuel pump, and sensor on side of throttle body. Truck has sat for 1-1/2 years, it had 1/4 tank of gas in it during this period. After I replaced everything and got it running, it was smoking kinda bad I put in fresh gas and lucas treatment, it no longer smokes bad. Truck will crank and run as long as I play with the accelerator. But once I let off the gas, rpms jump from 300 to 1400 about 4 times, then it dies. Please help, thanks!
Sounds like a fuel management system issue or a clogged intake or exhaust ract. The Idle Air Control Valve Colud be at fault as well.
I would check the fuel pressure first and replace the fuel filter. Then check the intake and exhaust paths for blockage.