i have 1986 f150 5.0 fi with duel tanks .the truck runs until it warms up and then it idles down loose fuel pressure then dies . i replaced the high pressure pump on the frame then the pump in the rea
the truck runs until it warms up the idles down the looses fuel pressure and dies . I replaced the fuel pump on the frame and fuel pump in the back tank and also the map sensor and still no change .
tank switch valve may be problem or pressure regulator at fuel rail most likely
I once had a car that had vapor lock. I replaced the gas cap with a new one, and the problem went away. Not saying that is your problem, just tossing out another easy enough to try and see if that is the problem.