Oh boy.. sounds like you replaced everything. As i was reading your situation it sounded like a distributor, But you replaced it with no prevail. This is an interesting one to try to figure out without having the car to see what it's doing or to run tests, From my end it's all guess work
So here is some of my guess work. I would think it would be electrical at this point. I would start checking the signals out of the ecm to the distributor. Making sure that signal is good. Then i would check injector pulse. Is this Car a stick or automatic. I am also assuming that the intake manifold gasket was replace not the valve cover gasket , unless it was leaking oil into the spark plug galleys , Cause a valve cover gasket i have never seen give you a vacuum leak. I would start by checking your signals from the ECM . If they are good and fuel pressure is good. Then i would look at components.. GL
