2012 Impala with 122000 miles. Ok so last week I was driving my car and it started misfiring but not too bad, just a slight vibration and throwing a p0302 code so I figured I would replace the spark plugs since it's been awhile. After I replaced them, it starting running very rough. I didn't even want to drive it. Also threw the p0300 code and the p0302 code went away. Today I replace all the ignition coils and it's still doing the same thing. Any ideas on the next thing at look at?