Okay so i have a 2011 GT with 92k miles and for about 4k miles it has been intermittently misfiring and fouling the spark plug in cylinder 8. At first i thought it was oil but now im not sure what to think. I was scared it was my piston rings but sometimes it misfires and i turn it off and turn it back on and it runs perfect. I’ve changed the coil packs already and no luck. It takes literally 50 miles or less for the plug to be black but i show no clear signs of burning oil and its an extremely wet black tip and it smells strong like gasoline. The only code i get is p0308. What do you guys think it could be? Oh and after driving it or revving it when i get out it stinks like sulfer