My brother is changing the plugs and cops on his 04 5.4l he got 7 out easily but the 8th plug is spinning loose but will not come?! It will tighten back up and then reloosen but won't come out! Anybody else had this issue? What did you do?

 

Lots of people have had issues. A quick search on these forums will bring up numorus threads about the 5.4 3v plug issues.

 

I've had plenty of problems and fixed them on my own 05 5.4l but nothing like this... and I've looked but not seen anything posted like this

 

If you got it out far enough to unthread it and it's still stuck, that's probably a good thing! Normally the part that is causing it to still be stuck in the head breaks off and the end of the plug comes out..

Get a pile of carb cleaner or some other carbon desolving chemical in there and let it soak, you have be lucky enough to still get the entire thing out!

 

Sounds like the far right pic. The threaded section broke loose from the plug.
Get a pliers and remove the threaded section then break the plug and use tool to remove the rest.