05 tl 6MT - 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!

 

why didnt you change the spark plugs back at 105k miles as recommended with the water pump timing belt major service?
Many ziners change them after 60k to keep the performance and mileage up.
When a plug gets old it has greater electrical resistance- the coil shoots a big zap of voltage at it - when it cant process it, that residual power makes its way somewhere- care to guess where?!

 

It is probably pretty obvious by now but you should have replaced the plugs. You need to pull them out and take a look at them. The problem could be somewhere else but you need to start with the obvious stuff first. Even with the latest and greatest plugs I do not run them past 50k.

 

If you have a melted coil I would guess that the spark plug is not tight.