360 4bbl

It runs good other than that, we're assuming. So, we know we have compression and timing. That means it's probably one of two things. Fuel/air delivery, or spark. Next time it just "shuts off", pull the air cleaner off and see if it looks wet in the carb/intake. If it looks like a desert, then it could be something as simple as a sticking float (shut), or perhaps something floating in the tank that blocks the fuel pickup screen. If it looks overly wet, could be choke going shut. If it's spark, well, could be several things.... and you'll get to go hunting...