OK. Next time it stops, pull off the spark plug lead and hold it near the engine. Please use a plier to hold the lead to avoid getting a nasty shock, Kick or use the starter to turn the engine to see if you are getting a spark. What we are trying to identify is the health of the ignition coil. It is possible that you have a failing coil. Once it reaches a certain temperature, it stops working. After it cools off, it begins to work again until next time. A failing coil may have same symptoms as fuel starvation. Once the coil has been checked we can move to the next step.