6.5 stalling after start up
 

I have a 1996 chevy 6.5 I have been battling problems with this truck since I bought it. Recently truck will start right up if air is released from fuel filter but if not stalls with n 30 sec and it just dies 90 % of time starts back up with in a min of cranking I have put a new spin on fuel filter assembly, lit pump, fuel lines from lift pump, back brand new fuel tank. Lift pump is wired so its running when key is in on position at 4 lbs pressure ( have mechanical gauge) I'm stomped not sure what to try and yes the pdm is on a cooler relocated also rebuilt injection pump all this with in last three months fuel cap venting not an issue ( has small hole drilled in)
So what's left any tips of help would be very help full and greatly appreciated. Thanks

Try running with fuel filler cap loose-if the vent plugs excess vacuum is created in the tank and can pull fuel out of the filter at shutdown.