[TheMAN]

the coils will die prematurely if you have bad spark plugs or bad leads... this is why I recommend replacing EVERYTHING... plugs and leads are wear and tear items... many people don't know this, but this is true! The coils will work harder and eventually die!

one other possibility is a short in the wiring.... a mate's car had some dodgy wiring behind the ECU panel and I found out an earth wire that was spliced was no longer insulated from the floorboard... this short caused one coil to be constantly energized while the key was turned "ON" but engine off and melted it! He learned a good lesson that day about doing electrical work properly on his car! I taped up that wire really good and it's been fine since!