do a compression test as that will let you know if the head gasket has gone around the pistons, also check the lights on the dash and see if you engine light comes on as i had issues with a knock sensor once that caused miss fire but only when the engine had been reved above 2k so may want to do a diagnostic chek on it too. there is a tutorial on how to do that also like i said check for moisture in the dizzy as that causes missfire.