Have a 93 that will start when cold. After driven for some time, I shut it off and go into the store, whatever. When I come back out, it won't start. Then I let it sit anywhere from 10 minutes to and hour and a half, and it starts again. Yesterday this happened 5 times. Wait long enough and it will restart. It has current; all the lights are operable, but the starter doesn't even crank. There's nothing. Wait long enough and it will start up as though nothing was wrong. I'm puzzled.

Check your battery cables, and the cable and primary wire connections at the starter (front of motor, facing radiator, down low) If there is no problem, the starter solenoid may be refusing to kick when hot.

When it does it, do you hear the "Click" from the starter solenoid under the hood, or no?

If you hear the click when you turn the key to start position, but no start, the starter drive is hanging up. You can have someone hold the key over to the start position while you whack the starter with a hammer (hit the starter motor, not the solenoid) if it starts right up, you need a starter.