I have a 1995 Chevy K1500 5.7 liter V8. At very slight throttle it has a very regular stumble. It is hard to explain but it cycles fuel no fuel, fuel no fuel. Having trouble finding the problem, no check engine light, no codes by flashing at the ALDL. I have replaced plugs,wires, cap,rotor, ignition coil, ignition coil module,pcv valve, throttle position sensor, fuel filter. Cleaned TBI, checked for vacuum leaks. Any ideas would be greatly appreciated. Very frustrating. Thanks