I have a 1996 f150 with a 302 and for some reason i don't have any fuel pressure when i first start it after i let it sit for probably an hour or more. i have to let it run for a few minutes or sometimes up to 15 minutes then it will start running fine. it seems like it just has enough pressure to idle then if i give it any gas it spits and sputters and will sometimes die. looking at the PID data on my snap on ethos the fuel trims go way positive into the 50s until it starts running better then it takes the fuel back away to where its suppose to be. i was first thinking the check valve in the fuel pump so i replaced the pump and filter and nothing it still did the same thing. so i moved on to the fuel pressure regulator so i took the one i knew worked off of my sisters truck an no change still the same. so i started thinking maybe the injectors might be bleeding off the pressure so i replaced all of them and still no change. i then checked the inertia switch and reset it just to see and still no change. none of the fittings on any of the fuel lines are leaking. it doesn't take long for the pressure to bleed off, in the time it takes me to shut it off, pop the hood and open it there is almost none left just enough the make it start again but it will run fine after it has ran a while then gets shut off and started within 30 minutes.
any ideas would be greatly appreciated because I'm about out of them lol

 

It sounds like you needed to put a fuel pressure gauge on before putting all those parts on it.
I would guess you may have a bad PIP sensor or ICM or a bad PCM Computer.

If it is fuel after checking with a gauge you may have got a FDM (fuel pump) with a bad check valve in it.