96 Prelude cutting off.?

I have a 96 prelude with the 2.2 liter sohc non vtec motor. It will crank and run for up to 20 minutes fine but then it will for some reason cut off. The lights and radio will all stay on but the motor completely dies. IT will crank back up after that but some times it takes a few tries to get it to crank after it has cut off. What could be causing this?