i brought my car to a local repair shop because of "check engine" light and they said a cylinder was miss-firing. does anyone know of a common problem associated with this? they said it shouldnt be a big deal unless i have a problem with my upcoming emissions test. i would like to get this problem fixed because i think its taking some power away from me. it also, pretty frequently, makes the car shake (noticable while in neutral waiting at a light say). but not always sometimes it sits smoothly. it also seems to make the muffler putter. if anyone knows what the problem could be, info would be appreciated.