I have a 2012 GMC Acadia and it’s running rough. Misfire on cylinder 6 so we changed the coil pack and spark plug and still nothing. There is white smoke coming from the car and a strong smell of gas which is dripping from the tail pipes. When we pull each spark plug one by one the engine stalls but when you pull 6 out it does nothing. Anyone know what could be wrong like why I’m not getting any fire to that one cylinder. Thanks