Wow, thanks 1lrover1 for the post. I know you posted it two years ago, but it was my situation exactly! I replaced the ignition coil because the code said #4 was bad, then when that didn't fix it I started to switch coils to see if the coil I bought was bad. That wasn't it. Returned the coil and searched the internet for a second time. That is when I found this post. Went to the truck ('07 Expedition) and took a close look at the wires coming off of #4 and sure enough that was it. It was a bear to try and work in the tight space. I got two butt connectors and cut the two wires, reconnected with the butt connectors and started the truck to test my fix. Sure enough, no misfire and the AC was working again. Shut it off, taped the crap out of it with electrical tape and made sure it was it wasn't touching the AC line. Good to go. Dealer suggested the plugs needed to be changed and wanted $600. I spent $3 on the connectors! Dealer probably would have found the bad wire and not told me and still would have changed the plugs to make the money...not this time! Thanks again for the post.