If it is a 3.8 its not a coil on plug.. It has 3 coil packs.. Its either the coil packs or the ignition modular ( the plate that the coil packs pug into).. I have coil packs at my house for the 3.8 if you want to swing by tonight or tomorrow and swap out the coil pack that is used for the cylinder 3.. If it stops missfireing then thats the problem, if it dont then you will have to go to advance and get a ignition modular.. they are 150.00..