I have 2006 Ford F-150 5.4 ltr
started truck up this morning and had a check engine light. Went to autozone they pulled the codes for me
code 300 and 307. First is random misfire the 307 is mis fire on cylinder 7. They told me it's either bad plugs...(I changed plugs about 4 years ago they are supposed to be 100, 000 mile plugs). Or the coil packs. The coil packs have not been changed as far as I know I have 165,000 miles on vehicle the plugs were changed at 106,000. Wondering what else it could be that's relatively easy to replace. Looking for feed back on this any help appreciated. I did reset the codes to see if they return.

 

Personally, I'd replace all the cops and plugs. Or at the very least all the cops since that's quite a while on the originals.

Use motorcraft parts.

 

Boots. The COPs are a frequently misdiagnosed failure point. Boots, contact cleaner and some dielectric grease, clear codes, and try it again.

 

I agree 100%

 

Just a heads up, Ford changed their service interval from 100K to 65K on spark plugs. You're probably due again in all honesty.

Replace the boots and springs as well as mentioned. Make sure you take a small piece of sandpaper or wire brush to clean where the spring contacts the coil.

If you DIY, make sure you torque the new plugs in to 28 ftlbs and use a small amount of dielectric grease to seal out moisture.

 

All of my misfires have been fixed with new boots and springs.