I have 94 F450 with the 7.3L IDI that shuts down after running for about an hour. It will start and run after sitting for about an hour. The truck will also lose power at times as well. It wont completely stall out but just wont run higher than idle.
Now I did replace the fuel lines from the tanks after I found a leak. I also replaced the lift pump and the fuel filter. My guess is the injector pump is going bad. I just want some feedback to see if it might be something else before I replace the injector pump.

 

Bypass the FSV, and might also like to check the fuel hose in the tank. Sure sounds like a fuel restriction, but could certainly be a failing IP, also might want to look for blockage at the pressuizing valve in the top cover of the IP at the fuel return and also make sure that fuel flows freely back to the tank.

Just check all the fuel lines and potential failure points. I recently cooked an IP from a slightly kinked hose, I guess lack of flow for cooling and pressure and such. But the way the hose was kinked slightly it was intermittent, though started off exibeting symptoms similar to what you're describing.

 

What Leroy said.

There's a black fitting in the top of your pump with a spring and glass ball inside of it, they like to get all gunked up on these old pickups. It will cause it to slowly die. Like running out of fuel but without the air spikes. Almost like you were choking the air to the motor bit by bit until it dies

 

how many miles on the engine, and is it the original pump and injectors?
pump and injectors are only good for around 150,000 miles.