Why does my car cut out while running even though it starts fine?

Okay, so I was driving the other night and my car just stopped randomly, it sort of just lost power didn't chug or anything. We left it for about 20 mins and it started again and ran for about 2km then did the same thing. Now it will start and will run fine when stationery but after driving for a little while it will cut out again. We have ruled out fuel pump, fuel filter and spark plugs does anyone know anything else that could be wrong with it at all. My thoughts are leaning towards crank shaft sensor or coil pack.. any other suggestions?