Okay so I bought this f250 about 2 months ago and was driving it around town never made any huge trips with it, but last week I was going on a 2 hour trip and 20-30 minutes in the truck just randomly dies on the highway, I had to pull to the left side and tried to crank it over, but wouldn't go. I had to wait about 10 minutes then tried it again and it started, but it was running rough. I pulled into a Walgreens and waited about 20 minutes until my dad came up there and we figured it was the fuel filter because the hose was too big for the fittings so we thought it was sucking air. Put the new filter on, started right up and drove it to a gas station not far away. While I was at the station it died again when I just left it sitting. I waited a little bit more and then started it back up (This time it took longer) I waited about 20 minutes in the shade then just said screw it I'm going to see how it does now. I went on the highway and it must of been about 20 minutes again and it dies. So we get it back to my house after that and start trouble shooting. My dad got a fuel pressure guage and apparently it was only shooting out 4 PSI so we went ahead and replaced the fuel pump, but it still keeps dying. I have put a lot of money into this truck so far and want to keep it running, but I can't think of what it would be. Please help. Info on my truck: 1986 F250 7.5 460 4x4, carbureted, automatic.