Took out spark plugs, cleaned them, then put them back in and car ran fine for 30mins and reved right out, then when i was about to change gears it made 3 loud pops and then took off even harder. Was running better than ever for another 15 mins. Then left it idling for 2 mins and runs like s**t again now. missfires under any load at all now. Cant seem to work it out, something must be fouling my sparkplugs...