So my wife's 2007 Lincoln LT has 63,xxx miles on it and it has been babied for almost it's entire life. Regular oil changes, maintenance, etc. It does have a 5 Star programmer set at 87 performance/tow and runs good; that is until a week ago. My grandson was driving it hauling a small 16' trailer from Idaho to Iowa and didn't hardly get out of Boise and the engine started to shake and shimmy with a big miss. He turned around and limped into our mechanic's shop (he's a former Ford certified mechanic) and he checked the code. The code read that No. 5 cylinder was bad. Took out the plug, which looked ok, checked the compression (200 lbs) and replaced the plug/coil. Engine still missed on #5. Let it sit over night, changed plug again and replaced wire and coil. Fired up and then #4 crapped out. Pulled the plug on #4 and the whole electrode was missing. Checked compression and it was 200 lbs. Replaced plug, coil and wire on #4. Fired up and runs like a new one. Wife is driving it around Boise today to make sure it will continue to run normal. Anyone have an idea about what's going on????

 

I think the problem is the original plugs ford used are garbage and should be replaced as soon as possible anyways my truck did pretty much the same thing a couple yrs ago when I had 78000 miles cylinder 4 electrode was disintegrated after I had plugs changed and all coils truck has lots of power again

 

I had the plugs changed at 60k, about a year ago, replaced with Ford Motorcraft plugs, but I am still miffed by #4 causing a problem with #5. Are they somehow related?

 

I'm not sure it sounds like the plug in 5 was also going bad although the wires on the coil plug in pull apart very easy and need to be careful when installing/ removing coil as that will throw a secondary circuit code maybe you have a loose wire on the push plug for coil itself that happened to my 06 I pushed the little wires back into the plug and truck instantly ran better hope this helps