5.4 stalls when warmed up
 

1999 f150, 4X4, 5.4, auto trans, a little over 93k miles.
Yesterday after driving it for 15-16 mile round trip (about 7-8 miles each way) when I got home and got out to disconnect the trailer it started sputtering for a few seconds then quit running. It would crank but not start. Temp was normal and verified 185 degrees with my OBD2 (equus innova 3140) code reader After it cooled down an hour or so it ran fine again. I do think I have a coil (or 2) going bad but this was much worse than a coil mis-firing.
Anyone have problems similar to this?

Any codes?

No codes.

Check your fuel pressure. Your fuel pump might be going out.

I thought of that. But by thought was, if the fuel pump was going out it would be more likely to act up at higher speed under load (towing a trailer up hill at 50mph) than at idle, which I was doing just a few munites before it sputtered out.
I don't have a fuel press tester - looks like I will soon.

The auto stores in my area have the fuel test gauge available to borrow. Check it if only to rule out that possibiity. It's about time to change spark plugs if it hasn't been done. I would put a couple bottles of Gumout for high mileage engines with PEA in the gas tank. And then see what happens. Cleaning the MAF might be on the list too.

Yes, fuel treatment is a definite. I was hoping to go thru most of what's in there now (about 3/4 tank) because it's been sitting a few months. I did put stabil in the tank before it sat.
Plugs were changed at about 45K (if they really did it) when I took it in for that brake switch recall.

Something I've started doing to my 02 is that I pour an ounce or so of Gumout into the vacuum hose that I pull off the brake vacuum booster occasionally. My truck started missing a little at idle and it cleared up afterwards. It may not be a good idea to pour a lot at one time because there is probably a lot of carbon buildup and breaking a lot of it loose at one time may not be good. I think I will remove what I need to and put a little in the throttle body sometimes since my throttle is sticking a little.

That's a pretty good idea. My only addition to that would be to do it when I'm sure it will be running/in use for at least 1/2 hour or more to be sure it all gets "sucked in" - used up so no residual remains.
I also need to find a vacuum leak, my 4x4 doesn't always completely lock in, I know the transfer case is working, plus when I'm going up hill towing a load, the air goes to defrost but returns to vents once I let up on the gas pedal.

Check the small hard vacuum lines behind the battery. I believe there's an accumulator back there too.

When you say "behind the battery" does that mean going towards the cab or the battery has to come out?

Battery has to come out.

Well, not sure why it quit that day. I've used it a couple times since then with no problems. Once was towing the utility trailer to get some lumber, other time was just running errands. Both times was for about 30 miles.