Ok, I thought I post what happened and what I did to fix it as I was unable to find anything out searching the forum:

So, I've got an 07 EL with 115k on it, the guy I bought it from had the plugs changed at 100k -they put the Champions in as they were the most expensive ($20ea) and touted as superior replacements as they're "one piece design" which is supposed to prevent the plug breaking off problem of the Motorcraft 2-piece stirrup design.

Anyhow, when I got the truck with 112k on it sometimes while driving the truck would slam and buck once or twice - the first time it did it on the highway I looked in my rearview mirror thinking I'd slammed into a brick or chunk of wood.... it hit HARD! but there was nothing there - so this got me thinking it was my transmission (I'd read that they had issues with the shift program). Anyhow one day the MIL (check engine light - Multi Indicator Lamp) came on, when I read the code it was P0300 - which is an intermittent miss. Really? C'mon, with all the electronics on these things it can't tell me which cyl was missing?!

So I reset the light and kept going, a few thousand more miles (and the occasional buck and lurch) and the light came on again - this time while towing our camper on vacation, I get it scanned and it's the P0300 again. The parts guy asks if when the plugs were changed the boots were done too - I have no idea, so he suggest replacing them as they can cause a miss too. $6 each for these boots. I asked if he thought I should do the plugs while I'm in there and he didn't think so. So $48 for the boots and another $160 for plugs?

Summitracing sells a boot kit for $32, I also picked up Motorcraft plugs from them for $12 each.

When I pulled the first coil (after blowing all the accumulated filth from around the boot) I didn't find any indication of arcing on the boot or spring so I pulled the Champion plug. WOW - the entire electrode was burned away! I'm talking about the base electrode that comes off the threads that you bend to gap - it's GONE! Ok, so replace that plug and now I know I'm replacing all of them. The next one, the center electrode is burned about 1/8" into the insulator and now the side of the plug is being burned/pitted. Again, no sign of arcing in the boot.

So, all the Champions were burned in some fashion and now with the motorcrafts in there it purrs like a kitten, no more code, no hesitation lurching or bucking.

So, I hope this helps anyone who's got questions about their sparkplugs or a code P0300

 

I get some bucking when down shifting from overdrive going uphills. I replaced all spark plugs 6 with motorcraft and 2 with champions. The reason I have 2 champions in there is because those 2 were replaced at a shop because of a misfire I had. Your post got me thinking. I am pulling out those 2 champions tomorrow to see what they look like

 

I tried posting a pic and it wouldn't upload to this forum - from now on Champions only in my Chrysler products!

I'd read your posts and was going to do the same thing (leave what I had and replace the bad one but then I got to thinking....)

They really weren't all that bad to do - the rear passenger side #8 was the tightest, I used 5 or 6 wobble extensions 3" long. It curved like a banana and came out pretty easy.

 

Yeah they are not that hard to take out. I just figured since they were new that I'd keep them in there. The champions are #5 and #6 so I shouldn't have any trouble

 

It's been said before and it's worth saying again-Never use anything but Motocraft plugs on the 5.4L motors. There is no reason to and every plug problem I have read about has been a Champion.