1988 Chevy Silverado fuel injection system

Got an 88 chevy 4x4 that has been causing a serious headache with the fuel injection system. Would appreciate any help. It has a 5.7 litre. The problem is only 1 of the injectors is working properly the other one just kind od dribbles fuel out. We thought it was a bad injector, replaced it and no luck. We had the fuel pressure checked and it was fine, and replaced the fuel filter. We also replaced the ecu and that didn't help either. We swaped the injectors in the throttle body thinking the auto parts store sold us a faulty one and we still had the same problem on the same side even with an injector that we know fuctions correctly. We also tried swapping the wires that hook onto the top of the injectors. We crossed them from how they were originnally and that didn't matter either. No matter what we've tried it's still the drivers side injector that won't work. Oh the other thing we tried, we got a whole different fuel injection system, just the top part where the injectors sit, not the butterflies, we got one from a junk yard and it didn't change anything either. So if anyone out knows why I only got one injector working I would reallt appreciate the advice. Thanks