Rather than rely on the light, hook up a handheld OBDII scanner that has a datalogger or live view. It will be obvious which cylinder is having the misfire then or what is causing it.
08 S197 GT Auto: FRPP Strut Tower Brace, FRPP Bullitt CAI, Bama 91-P Tune
Pending upgrades: Shaftmasters Aluminum 3.5" DS, FRPP 3.73 gears, Axle back exahust (?)
Originally Posted by LostBoyz
if you are getting 29mpg in your 5.0, you aren't driving it correctly