will start fine, but drive for 20 + min and shut off will not restart for 20 min

i have3 relays fuel pump,auto shut down,starter, have replaced all but still have problum thanks for the comeback

If you have replaced all relays then the problem could lie in your ignition system. I would try these things then get back to me: Jump the car after a failure, Try tapping on the starter without damaging it while a friend turns the key, test your starter solenoid with the car off (you should hear a click), check to see that your alternator is working properly it should give off more than 12v while vehicle is running. Also check here for more possibilities - http://www.jeepforum.com/forum/f12/91-yj-intermittent-starting-problems-116281/

it turns over fine but will not fire it will push start and fire run till i kill it again then will not fire tell it sets for 10 to 20 mins then will start and run till i kill it again