JWA: Thank YOU so very much!!! My anxiety level has decreased tremendously thanks to the thread "Testing Spark Plug Holes". Unfortunately the blownsparkplugs.com site seems to no longer exist, but I did find this site which was also helpful: plug site

From that site and the fact that I've gone over a year without a problem (and put 10K -15K on the plugs), I think I'll just replace all the coils again with Motorcraft (I'm getting better at this) and see how it runs. All the misfires started after I did the cheapo coil change). If I get errors, then it's plug time.

Bill's testing of how much torque it takes to strip out the threads in an aluminum head was exceedingly interesting!

You're also correct in that online are mostly posts about problems, not successful plug installs. After a foot operation five years ago, I spent my recovery time reading about the results of that operation online. I became nearly convinced I'd never walk normally again, and had ruined my life. As you might expect, It went terrific and I'm walking normally.
Thanks again!!
PS: From your profile picture you're a dynamite 68-year old!

 

She is indeed a lovely lass----I'm happy being a guy but if I'm ever to be reincarnated I'd want her form and smile!

So yeah reading nothing but problems can be disheartening and put us into a funk, assuming there's not but trouble ahead. While knowing the possible problem areas up front is helpful we have to keep in mind the instances where it goes trouble free.

The site you found about spark plug hole threads simply reinforces what so many of us already know----the head design can be blamed and possibly some holes did have quality issues but the point made about heavy handed bad installation could be the biggest problem. We can't dismiss some spark plugs could have been installed incorrectly right in the factory.

Your misfires could be related to the COP's but just as importantly the boots could be an issue too. Because I use Motorcraft DG-508 COP's that have a good quality boot included I've never had a misfire due a bad boot. When I change plugs the boots are carefully inspected and replaced without hesitation if they look suspect. I'll look carefully at the end that slips over the spark plug---if its bulged out enough it might allow moisture to creep in its time for a new one. Adding just a dab of dielectric grease in that opening is helpful to exclude moisture too. Same with the wiring harness connector---just a little is all that's needed.

Shop eBay, Amazon and even RockAuto for the COP's---Motorcraft is my choice but the Denso brand is supposed to be the actual manufacturer of the Motorcraft brand so either will be good. I did find a stupid good deal on the DG-508's' paid just over $25 each but that price is no longer available. Shopping around pays off but be advised some eBay sellers mislead a buyer by listing Motorcraft plugs with COP's as a "kit"---they carefully hide the fact the COP's are NOT Motorcraft, the unobservant just assuming all the parts will be Motorcraft.

Anyway proceed carefully and deliberately and you should be fine. If something doesn't seem right stop, post your question or concern here and we'll do the best we can to work through it with you.

Best of luck with all this!

 

I’ve got these: (not yet installed) 10 MOTORCRAFT IGNITION COIL DG508...
when I installed the cheap coils I smeared all of them with silicone grease. Then I thought the primary connection was intermittent (wrong....different error code.)

To fix what I thought was a poor primary connection I got some silver-filled electrically conductive grease. (0.5 ohms across a 1/4” piece). Then I realized the problem was in the coil/secondary.

Now my plan is to put just a small dab on both ends of the spring (NONE ON THE BOOT) of the new coils to enhance the connection (Q-tip), as well as using dielectric silicone on the outside. I hope to not be able to tell if the engine’s running or not.

 

That's a good deal on the COP's---I've bought from that same seller for the same price but in the V8 sets only. For that money there's absolutely no need to look for cheaper aftermarket parts.

I'd not use anything but the typical automotive dielectric grease and sparingly at that. No more than a dab inside the bottom of the boot where it seals around the porcelain part of the plug. Another small dab inside the wiring harness connector terminals at the top of the COP.

Conductive materials might cause misfires more than prevent it as you want the current to stay inside the COP housing and boot. When the boot is in good condition its all the insulation you need for good ignition.

 

Bumped the wrong thread----sorry 'bout that!