I have a question about a 1997 GMC SIERRA?

First thing you'll need to find out is,what you are loosing.You say it will not restart for at least an hour,so you need to take the time to do some basic checks.Take tools with you or whatever it takes to do some diagnostics.Even a mini screwdriver will help.You can use it to check for spark,check for fuel pressure,etc. Two things come to mind. Some systems leave the fuel pump relay energized to keep the pump running,the relay may be overheating. Most run through the oil pressure switch. The switch could be getting weak or oil pressure too low and the fuel pump is shutting down. Good Luck!