1989 f250 losing prime while running
 

Hi i have an 89 f 250 7.3 idi and my current problem goes as is. I will be driving down the road and after about five miles of driving the fuel filter light comes on and the truck slowly runs worse until it finally dies on me. So when i pull over i bleed all of the injector lines then it will start up and run for another 5 miles or so then die again. I think that it has to be Ir in the system but i dont know where. I have replaced the lift pump im just worried that it might be a defective one. Also i took the injector pump off and cleaned it up and inspected it and it seems to be working fine. It is still sending fuel to the injectors. Im just worried that it could be hot swelling or what ever its called when it gets hot and can no longer push enough pressure. I havent poured water on it yet to check it either. I also just had to repair the frint sending unit so one if the lines on the tank could have a bad seal but im not sure. I guess i should have started with saying this happened the first time when i seafoamed my back tank let it sit for 3 months then used the tank and sucked alot of rust through the lines and had to changed the fuel filter. And it hasnt run well since then. The fuel filter light still comes on and it dies so i am at a loss and i need this truck running to get to school so any help will be greatly appreciated