I am sure this has been discussed 1 million times, I figured I'd add my 2 cents, and relate it was much easier than I anticipated:
@ 86K miles I figured it was time for a plug change (no issues, just don't feel comfortable adding another 20K.. plus I've lived the horror of "stuck plugs from the early 2000's 4.6l... I still have the tool I made to helicoil the hole)


Issues:
I wanted Iridium plugs (Autolite)
They sold me the incorrect plugs... 5/8 hex..(must have been for the 2V 4.6)

It turns out the installed plugs are 9/16 hex.. to me this is non-standard => my spark plug sockets with the "rubber" plug holder aren't the correct size.


Took the wrong plugs back, got the new ones, compared to a removed plug exact match... {Motorcraft double platinum HJFS-24FP,}
These are a huge improvement over the 4 thread plugs the (2002) Mountaineer had...(I called them the ejector plugs)

General sequence I used,

I start with a 2X4 with 8 holes drilled, lets me hold the old plugs in the correct order and look for any issues.
One cylinder at a time
remove the coil, inspection showed no issues
vacuum the hole
squirt WD40 in the hole
unscrew plug
remove the plug w/ a magnet
Check gap & anti seize the new plug
install plug using a vacuum hose
turn by hand, final torque 106 inch pounds (per the shop manual), that's about 9 ft pounds
(I've read folks suggest 25 foot pounds)
reinstall coil and anti seize the hold down bolt.

Using bungee cords on the passenger side to hold hoses out of the way made all the plugs accessible. not having the "holder" socket means I needed a magnet to get the plugs out, and a vacuum hose to put 'em in... not too tough.

Removing the air plenum allows access to all the drivers side plugs, the #8 (most rear) took a little patience. All in all, not too bad for a modern V8.

The inspection of all 8 (old plugs) showed no issues, the maximum "gap", was .045", spec for new is .039-.043" All (8) had that tan color on the insulator,

I have since learned they do make a 9/16" spark plug socket (with the little rubber holder)... I don't need one today, but I'll have to add 1 or 2 to my tool chest.

To the Ford engineers that fixed the spark plug issue (4.6 & 5.4l) good job , too bad they goofed it up in the 1st place.

 

They goofed it up twice.

 

I'd recommend 25 ft/lb, 9 is just not tight enough. You also do not need antiseize if using Motorcraft plugs.

 

Even at 25ftlbs people still complain of raw fuel odor while running