So two days ago I put a new header, cat, O2 censors, and tailpipe on the Jeep. Ran great except for a slight vacume leak which I think i fixed. I started to drive up my driveway and the Check Engine light came on, plugged in the OBD and it said P0306 or cylinder 6 misfire. Cleared it, didnt come back on. Just wonderin if anybody else had this problem and mabe the vac leak caused it.