Running rough all of a sudden!

[FarmageddonNRO]

So, I live in Montana, my 91 XL has been running great since I replaced the spark plugs, plug wires, fuel filter, fuel pump relay, air filter, etc. I took some friends to a town that requires a trip over a pretty steep pass, we had some problems with the brakes getting hot and melting my manual hubs, which is an obvious fix. But on the way back we had to deal with my 91 losing power then cutting out completely, causing us to have to pullover. When we would pullover we would wait like ten minutes, it would start up fine, and about 5 minutes the truck would lose power again, and die, causing us to have to pull off the road again. We then made it to a bar on the way back, let it cool down for over an hour, we drove the last 35 miles with no problems. After that trip though the truck has been running really rough when you hit 55+ MPH. I'm curious of this might be something simple like an O2 Sensor, or could the fuel pump be on it's last legs? All the symptoms lead up to a fuel related issue, but who knows at this point. Any ideas would be helpful, I have to make a 2200 mile cross country trip and would like to address the problems asap. The check engine light has recently started coming on as well, I guess I could start by putting on a computer. Thanks

 

[MrShorty]

If the CEL has been coming on, then, you're right, the first step is to get codes from the computer. We have a few threads here that describe how to pull codes with nothing more than a paper clip, if you are interested in reading them.

In addition, any time I suspect a fuel issue, I put a fuel pressure gauge on it and check the fuel pressure (when the symptom is occuring).