My buddy has a 1988 Ford Bronco II with the 2.9L V6. We've replaced everything fuel-speaking from the tank to the regulator and most recently the relay.
The truck starts and runs long enough to use what fuel is in the lines, then it dies. It's not actually sucking the lines empty, just running (then dying) long enough to use what fuel would be in the fuel lines.
We've asked every mechanic and shade tree-mechanic we can think of (and that's alot, here in Texas) and everyone's scratching their heads to figure it out.

When (note: NOT if!) the truck dies, if you let it sit overnight, approximately 8 hours, it'll start and run for about 10 minutes before dying again. We've checked pressure from the fuel pumps, and it's squirting gas but not shooting it out. Kinda like a little more than gravity-feeding. It seems to build pressure enough to start, but then immediately looses it's pressure and dies.

Please, somebody's gotta know what's going on here.
If you have any questions, don't be shy to ask. I can tell you anything you need to know, if it'll fix this problem.

 

"We've replaced everything fuel-speaking from the tank to the regulator and most recently the relay."
Does that include the fuel pump and the tank itself?
Thinking out loud: it could be a weak fuel pump or something clogging the fuel pick up. There should be a screen.
Or it could be that the venting for the tank is clogged. Do you get a giant sucking sound when you remove the gas cap right after the engine dies?

 

Yes. Both fuel pumps (there are two: one in-tank, one frame-mount) have been replaced within a month of each other.
We dropped the tank, cleaned it, and resealed it. It's on it's fifth new fuel filter.
The fuel pickup is fine, as we've checked it every time we've had to drop the tank (4 times, now).
Will check for the sucking sound, removing the fuel cap has not been the first thing tried when it dies.