After reading about coil packs, plugs, wires, cops, and on and on. After replacing plugs and wires and still having the missfires under load. I read on and found a few threads saying to use silicone grease in the boots. Well guess what ? As I cussed pulling out the wires from the plugs again. I noticed the little streaks where the spark traveled down the inside of the boot and of course to ground on the head. I believe cylinders 1,3, and 7. I loaded up all 8 with the grease and went for a little test drive. I have not had a single missfire since.
Thanks for the tips and I hope this helps someone else!

 

This is great news!!! Thanks

 

Amazing.. I though I was chasing a dead end. I have been working at getting the dealer solve this problem with absoutly no satisfaction. What type/brand dielectric did you use??????

 

I am pretty sure it is Permatex brand. I did not really pay attention. It is available at any parts store. From what I have read It should be applied at every tune-up but I bet it is not!!!
Good luck

 

Still going and no missing. I put the truck thru a pretty good test today. I put the gooseneck horse trailer on and hauled two horses down the road. No troubles and the truck pulled like a champ!

By the way took the horses in case I needed a ride HOME!!!

 

Well, did mine up too .. Purchased my di electric grease @ Radio Shack - It comes in a pressurized can lol - never seen this before , always used Permatex brand..You had to be carefull when you pull the trigger - the grease really files out of there . I 've had so many COP problems in the last three months that I just replaced everthing with original OEM parts - 8 COPS & 8 19lb type 2 (oem upgrade) injectors. I really thought I over did it on the di-electric grease...I coated the inside of the boot real good (the grease got in the springs) I ran a bead at the top of the boot and then installed , when installed I then coated the electrical plug ins and also , what most people forget to do - I coated di-electric at the top of the spark plug hole in the head and filled the gap between the boot and the head to keep water out of there..It runs Great!!!!Sounds healthy again - 160k miles on my 5.4L and thru reading these forums and getting TON's of great advice, has me looking forward to many more years with my 98 ford - (the supercharger is in route, can't wait to do that lol)

 

Have ya all learned anything?
Clean and seal everything and look for carbon tracks.
If the tops of the COP have the potting seal broken from heat and age, cover it with silicone rubber sealer.