Truck will not start

I drove it to the store and it ran fine but when I tried to start it to go home It turns over fine but would not start at all. After twenty minutes or so it fired right up like nothing was wrong and ran fine all the way home, but would not start again once I got home. I tried it the next day and it cranked fine. Drove it to the store again and after shopping it would turn over but not crank. Twenty minutes later it cranked fine.