my 5.0l f150 4x4 is driving me nuts and broke.In really hot weather in stop and go traffic it starts to stumble then quits like its starving for fuel.After about 2 or3 min. it will start up again but you have to feather the throttle or it will puke out again.So far i have changedcap,rotor,wires,plugs,ignition coil,ignition module,fuel filter,throttle pos. sensor,had the injectors flushed all to no avail.Finally i had to break down and bring it to those crooks that call themselves (FORD QUALIFIED TECHNITIONS) AT THE LOCAL DEALERSHIP.They hooked it up to THE SCOPE!! and told me nothing was wrong electrially. Then they told me the fuel pressure regulator was reading high and the isc solinoid was no good.So like the fool we all are at the dealer i gave the ok to go ahead and change them.I got it home and it seemed to run fine. A few weeks later it got hot again,i was stuck in heavy traffic,and guess what? STARTED STALLING AGAIN.
Please help some one because i cannot afford another $500 repair at the dealer

 

I had this same problem in a 93 F250. The engine would choke and die in hot weather (It is hot year around here) After the dealer intstalled new fuel pump, filters, lines etc . . . I figured out, it was a vapor lock. Try unscrewing the gas cap. Mine would hiss from the build up of pressure. I would let it sit for a while and it would start just fine. I finally drilled a small hole (very) in the cap to relieve the pressure. It never happened again. The damn dealer still insisted this was not the problem.

I hope this helps and you solve it! These types of problems can drive you nuts. I have sold vehicles for less.

Good Luck.