Changed my plugs about 7 months and 10K miles ago and ever since I've been haunted by a mysterious rough idle. I installed the Champion plugs and I thought I was happy about that.
The engine showed no codes. I just could feel it shudder ever so lightly. I replaced the boots with no change to the situation.
I had tried to convince myself, that is just how she runs now.... but I just couldn't get used to it. Recently I pulled a loaded trailer across the country and I really could feel it shudder when I was sitting idle - still no codes.
I decided to pay for a diagnostic ($90) at a dealer that I trust. They said they isolated the miss to the #8 cylinder but agreed that it was very subtle and showed no codes. Then they advised me to go ahead and change the plugs since I was at 91K miles now and informed me there was a potential issue with these plugs. The service advisor was very surprised when I told him I already had changed my plugs and followed the TSB. He decided to just let me talk to the tech since I knew more about it than he did.
He told me he had switched the COP on #7 and #8 and the miss did not move. He said he also tested the fuel injector.
As soon as I told the Mechanic I had installed Champion plugs he said "thats the problem" and advised me that he has seen this before. He strongly recommended I switch back to Motorcraft plugs.

Well - today I put in a new set of Motorcraft's and she purrs just like a kitten.
When I was a kid messing with my hotrod mustangs I never trusted champion plugs. Wish I'd stuck with that!
Anyway - Today my '06 has 91K miles on her and she's running as good as the day I bought her (she had 12 miles on her that day).

 

Thanks for the info! Getting ready to do plug change, think I'll stick with the Motorcraft.

 

Sorry you had problems with the Champions. I have heard sporadic complaints about problems, but most reports were positive. That was why I put the Champions in my 2008 Screw two years ago. I now have just over 21,000 mi. on them and, as with your truck, it runs like the day I drove it home. Just another perspective. Best to use whatever you feel most comfortable with.

HYPO