I posted a thread on here the other day about valvetrain problems, and I used a K&N filter/Lucas/Mobil 1 oil, these things didn't cause the problem, 24 hours after changing the oil the customer called up and said that the truck had a knock. So I went to look at it. One of the spark plugs(bosch +4) had backed out and the coil broke off, messing up the threads in the head. Has anyone had any luck using a thread chaser on the 5.4 heads?

 

Here are some threads that discuss this issue.
Blown Spark Plug
Jes
edit: btw people have used helicoil with success, so that may be an option.

 

I would replace the coil and put a Helicoil in to repair the threads. To be on the safe side I I would rig up a small hose that would fit into your spark plug hole in the head and attach it to your shop vac to make sure nothing fell in "it's not very likely but just to be safe. A lot of people never use antisize with aluminum heads or over torque them it is a very common problem and many companys now make repair kits but helicoil is been in the biz a long time.