I have an 04 f150 with a 5.4....i replaced the fuel rail pressure sensor and another fuel part that sends power to the fuel pimp i can think of what it is right now but its located up near the spare tire....anyway my problem now is i can drive for miles and nothing happen then all of a sudden it will just stall and wont start for a while then outa nowhere it fires right up.....it does it when i drive or when im sitting still...thought it might have been the fuel pump but i had it on the computer and its keeping a steady 40 p.s.i at all times....i have NO IDEA what to do......please help.......i also only get 9mpg...

 

Does it die only when it is idling? Will it start if you push the gas pedal slightly?