If it shows a mis-fire chances are that it is more than once. I remember a thread from a while back that stated that the engine had to mis-fire several times within a certain time period before it throws a code. I experienced the mis-fire code when I first got the car over 1.5 yrs ago. took it in and was told it was bad gas. I have never had the problem again, but I have also used 93 octane ever since.

 

My CEL was on for about two months. While I was driving everything was fine. If I stopped my Traction Control would turn off, and my car would ride rough, sluggish, and shift very hard from 1st - 2nd gear. Finally took it in to a mechanic and I had a P0302 code on my car. Changed the ignition coil on it last night. Light has been off since. Car has returned to its normal self now. Hope this helps out any.