[RayChez1]

I believe what is wrong with your water heater is that you have a bad thermocup. They need to be replaced every so often. What is happening is that once your heater reaches certain temperature it is turning off and will not reignite because of the bad thermocup causing the water to cool down. They are very inexpensive and can be bought most of the time at a local Home Depot or ACE hardware stores.
Good luck!