I know no one has replied in a while, but it's worth a shot. So, when I changed the spark plugs, I also did an oil change....while I was changing the oil filter I accidentely broke a sensor wire. I'm not sure what sensor it is (it is located by the oil filter a little below and to the left). So, I repaired it (so I think???)..could this be causing the problem (does it not have a good connection??)...I unplugged it and started and it ran like it was before (surging/misfiring). My check engine is not on. THANKS