i got 160k miles on 6 of the 8 COPs and they are acting up. i have a Standard set on order i trust the name for years. just a note for those of you new to COPs: i was new a few years ago with the 4.6 in my van and now th 5.4 in the excursion. the boots should be the first place to look. you will see white marks where the spark goes thru and there are some deals on ebay for the boots like 8 for 20 bucks with the springs. anoither thing that happened to my excursion is the water outlet under the t-stat broke where the "fetuccinni" gasket goes and it leaked very little but enough to get into the spark pluc hole and screw up the boot. and i gues eventually the COP. one thing i want to ask the group is: is there a way for the COP to be bad and read the right ohms? my haynes manual gives the range for these readings but i think with time they become suseptible to heat.
plo

 

Do search on fellow member "Sequel2Spud" who in a thread titled" 97 Engine misses @ 60 MPH" describes how to throughly test coil packs. There is a little more to it than just measuring resistance.

 

I love this forum! great answer. I just want to add that moisture in the hole at least in my case was a leaky manifold gasket. with 160k I can't complain.

 

Here's the link to the thread.
https://www.ford-trucks.com/forums/5...es-60-mph.html