There are 2 things that I can think of, that are causing your car to do this.
1: Alternator is starting to go bad/connection to alternator. As it seems to be happening more often, it sounds like the alternator is getting hot and putting the electrical system out of whack.
2: Short circuit from a positive component in the vehicle to the body. Sometimes it will arc and make it seem like the engine just died, but will restore itself fairly quickly. Make sure that you have the protective covering on your electrical connectors and have your alternator tested.