Car stalling

So while I am driving my car is randomly stalling/shutting down. Normally it is after I have decelerated or after waiting at a stop light, and on occasion it seems that the engine does not engage at low speeds (it kind of hiccups, and then after a second or two it reengages). When it stalls the car shakes for a couple seconds and then shuts off, but I do not hear anything. Once the car has stalled/shut down I cannot give it rpm's, but the electrically continues to run (ie AC, dashboard, etc.). In order to restart the car I have to put the car in park, turn the key to the off position, wait one to two minutes, and then turn the car on again. It happens inconsistently, but often (ie it does not happen at every light, but it happens once or twice a day). I cannot tell what conditions lead up to the stall/shut off. I have tried adding HEET to my tank with premium gas to see if it was possible that I got water in my gas tank, but that did not solve it. Thoughts?