I drive this vehicle about 100 miles on the interstate atleast twice a week. Last October, I was riding down the interstate and my "service engine soon" light was flashing and the vehicle was shuddering really bad. I had the code read at o'reileys and they told me it was a cylinder #5 misfire. I replaced the coil and nothing changed, so after some thinking i changed the fuel filter. I was thinking that since the problem only happened at interstate speeds and maybe the filter was clogged? Did not fix anything, it added problems. Now the truck shakes terrible at idle. If you get over 1,500 RPM then everything smoothes out. Next thing was the service engine soon came on again, except this time it showed a #4, #5, and #7 misfire. So I looked it over and the #7 coil was not bolted tightly. i tightened that up and still wasn't sure what to check on #5, so i just decided to change all the plugs. When i pulled #4 spark plug, this is what i saw
So after replacing all of the spark plugs, nothing was fixed. I gave up and took it to Ford and asked them to diagnose the problem. $100 later, they told me that my #7 coil needed to be replaced, and that i had low compression in the #4 cylinder most likely from a "cracked insert". I replaced the #7 coil and with the new coil and plug, it still doesn't effect the idle. You can unplug it while its running and it doesn't effect the way it runs. I pulled the #4 plug again and luckily the insert came out with it, i replaced it and got it all put back together and nothing changed. It is obvious that #4 is blowing oil / gas out the spark plug hole because the boot on the coil is soft and soaked with whichever fluid it is. So after some thought i got a picture of the #4 cylinder spark plug hole, and it looks like this.
and in the same cylinder,
Sorry for the long post, but I am completely stumped on this one. If anyone can help figure out what this is, that would be great. I really don't want to have to pull the head, but if thats what has to happen then that is what has to happen.