My Father in law has a 1987 F-150 with a 350 , auto, it has around 100,000
miles and for the last 4 months it will randomly stop, he will be going down the road at any speed and it will just kill sometimes it will start right away but most of the time it will have to sit for 15 or 20 minutes. he has had it on scanners but they cannot get it to kill while on the scanner, they have replaced most of the electrical parts, ignition module, pick up, etc. they ran LP gas into it when it was killed and would not fire so they think that its not the fuel pump. it has been good for the last two months then started again, one day it killed 3 times has anybody had any experience with this?

 

Try relacing the fuel pump relay and check the small black wires attached the the battery negative terminal, one of them is the ground for the fuel injecton system