More info needed before anyone can even hazard a guess..
IE: engine stalls or looses all electrical power?
What's been done to it? IE: tune up, filters, fuel system flushed, etc.
When does it do it? Sitting at idle for 30 minutes, driving for 30 minutes, highway, city, etc....
Fuel condition? IE: full tank, almost empty, old fuel, new fuel, etc.
Sounds heat related if it will run for 30 minutes and stall/die.
likely causes: Vapor lock, overheated electrical component, etc.
But that is a pure WAG without more info.
You're lucky your mechanical fuel pump still works after sitting 10 years. The diaphragm usually rots out and makes the pump useless. That's what happened to my 83 when it sat for a couple years. I cured it by yanking the 3.8/c5 out for a 302/T5.....
You'll need to bring a spark plug or spark plug tester with you when it stalls out I'm assuming after letting it sits it fires again. I had a 82 lx with a 5.0 that would run about 20 miles on my way to work, then die. I'd let it sit about 5 minutes it would fire and run fine as long as I stayed off freeway. I changed my electronic ignition module box, problem went away. You need to figure out if your losing fuel or spark. Also bring a can of starting fluid with you. Again spray a shot down carb when it stops, if it fires then runs, you have a fuel pump that's failing. If the fuel is 10 years old, which I hope you drained and refilled, you need to get it out. If you have access to a fuel pressure guage, you want to run a test. Let us know what you find.