BYmechanic

I have a 1989 Ford f-150 5.0L engine manual transmission. I recently had a no spark condition. The vehicle had the original high pressure fuel pump so I replaced that and the fuel filter. Unrelated but needed replacing. After testing the system I found it was the PIP in the distributor. I replaced it with a re manufacture one from Pep Boys, still no spark. I was stumped. I had it towed to a local mechanic who said the distributor was bad. He replaced that and the computer. $515.00 later I picked it up but now it had an intermittent misfire. With a manual transmission that's really bad, bucking a lot. Come to find out he never checked the timing. It was off 20 degrees. Now I'm reluctant to take it back there to diagnose the misfire. It seams as though the engine turns off for a fraction of a second. He did mention he took a fuel injector connector off at one point. Could that be the problem or maybe the new computer? It also felt to me that the new distributor cap was looser than previous ones I had. What could cause the bucking? The engine runs good, no hesitation, just intermittent misfire.