Hello guys I'm new here but I don't know where else to turn.
I'm not a mechanic professionally but I can fix pretty much anything that goes wrong with my truck so I guess in other words I know my way around an engine. I have a 1991 f150 with a 4.9 straight 6 in it. I recently bought it knowing it needing some work so I wasn't surprised to find it had more problems that originally expected. My problem is that when cranking an driving the engine shakes an sputters violently and it has trouble cranking when cold. I have replaced the fuel pump, filter, relays and fuel pressure regulator... The plugs and wires and the ignition coil, the alternator and radiator. I am at a complete loss. I've done everything short of replacing the fuel rail and injectors. After driving about half a mile the sputtering will let up a little but it will still sputter with hard acceleration. It feels like while driving that the fuel lines have air in the system. That's just a guess however.
I appreciate any help you can give me

Thanks

 

Sounds like an ignition issue. Check timing and adjust if necessary. Have you checked for computer codes?

 

I haven't checked the codes not really sure how. The local parts house said they couldn't cause it was to old. I had my mechanic check the timing and he says its fine. That's what I'm saying every obvious fix has either been fixed or ruled out.

 

Here's how! Fuel Injection Technical Library » How To Run a Self-Test

 

Double check that your spout connector is in place. I had a smog tech remove it and not put it back. Truck started running really weird.