In 2019 my '07 was missing some under load in OD at low speed. It was not as bad in 1,2,3 as the TC hid it. I changed my '07 5.4-3v plugs in 2019 at 69,000 miles, two gave me a fit, one was #8 way back under the firewall, just the metal shell with threads came out, leaving all the porcelain and lower metal in the head. I had Lisle 65600 Plug Removal Kit but could not use it there because I could not reach the plug top to break it even. I had Lisle 65710 Porcelain Puller Kit overnighted to me, piece of cake then as it snapped onto the plug top, the was locked on when the tube was slid down. Together they make a Lisle 65700 Set.

Well, yesterday, we took the '08 Mustang with 4.6-3v out for a 250 mile drive, it's a 5 speed, no TC. I could feel the same miss even in lower gears, it was "sporadic". If I took it easy on the gas, no miss. Car has 36,380 miles on it. A little early for needing plugs, but I had a set in a drawer, new Auto Lite HT-1s. This morning with the car cool, I removed the coils and with air hose blew trash away, then squirted a little Kroil into each plug well, then I loosened the plugs a quarter turn and did something else for awhile. I went back to it maybe an hour later, 8 plugs came out, no hitch. Truthfully, they even look OK. I did apply some nickel anti sieze to the lower barrels and very little on the threads. Put them in, 25 ft lbs.

Buttoned it all up, car runs like raped ape now, no misses.

Surely was OEM plugs init, white paint on the coil ends. I also found that like on my '07 5.4, the plugs apply greater pressure to the spring from the coil.

36,380 miles.I

It went so smooth, so clean, so easy, I think I'll change the '07's plugs at or just over 100K next time.

I'll be using Motorcraft or Auto Lite plugs either way. I have all the Lisle tools if ever needed, but I've read of a few fails of the Champions where the hex breaks free of the lower threaded portion, and no tools to reliably address that failure.