ok, car started running rough - 110k miles - orig plugs. found far right front cylinder coil was melted and was not operational - no spark - slightly over heated looking - smelled burnt. replaced coil $95, did not change plugs.. car ran ok for about 200 miles, started running rough again, pulled apart, same coil was completely melted, fell apart when removed and now is melted in the spark plug chamber - real mess, do not know how i will clean out, but what is causing coil to over heat and melt??? help!