Im wondering if a faulty overflow valve will cause starting issues? I've replaced all the rubber lines already so it isnt that. The truck will start for about 10 seconds and then die, then you crank it and its like its lost prime. So I prime it and it'll start if I press the throttle and it runs rough like it got air in the lines to the injectors. Could it be the overflow valve, it doesnt make the squeak noise anymore when I prime it.

 

Check your screen filter in your fuel heater. It is a fine mesh screen before the fuel filter. If it clogs, it will not allow enough fuel to the injection pump and cause problems like you describe. Also, your owners manual discusses maintenance on this.
Chris

 

Yeah that gets cleaned at every fuel filter change so I know it isnt that. My overflow valve used to make a squeak noise once it was primed and i'd hit the primer a few extra times to push fuel through the overflow valve. Now it doesnt squeak anymore.

 

It's got to be the overflow valve. Do a search for Marty Tomkins, he's got the best deal on them. I think like $35 plus shipping.

 

If yours is not a one piece valve, you can take off the top fitting (being VERY careful not to lose the little washer(s),spring and copper seal). And stretch the spring a little.

But the way you describe the problem it really sounds like an air leak somewhere. Check the wiring connection at the fuel heater, mine started sucking air from there and would act similar to what your describing. Had to spray it with brake cleaner and then filled it with silicone and shoved in the connector. No problems since.
Also inspect the the 90* hose from the heater to the l/p, it will crack and suck air.