Well i changed the oil today, and when i was finished i fired up the car to let it ide for a bit and make sure nothing was leaking and everything was fine. So i got in the car, put it in reverse and started backing out like i always do. after about 10 feet or so of backing up, it starts running like shit. It barely holds idle and when i hold the revs around 2000, it misses and stutters a lot. It almost feels like a big vaccum leak but i checked everything adn nothing seems to be leaking. I pulled the plugs to see if maybe one or two of them had fouled but they all look good. Any ideas on what it could be?