looking at engine   left bank is 1234 right bank is 5678

having put over 120,000 miles on two V10's I quickly learned to buy a cheap scanner and carry it and a spare coil, and the few tools, necessary, and can of compressed air to replace a coil along the road! saved my but a few times on long distance road trips!

LouSWPA wrote: having put over 120,000 miles on two V10's I quickly learned to buy a cheap scanner and carry it and a spare coil, and the few tools, necessary, and can of compressed air to replace a coil along the road! saved my but a few times on long distance road trips!

OK Steve answered the compressed air question. To Jay's question, I'm not sure if it is the coil, or the boot. The original coils were a one piece affair, coil and boot assembly. Later on, I discovered individual pieces, coil and boot separately. I think, sometimes at least, it wasn't really the coil, but rather the boot. Because, like Steve says, the plug and boot resides in a well, and 'stuff' gets in, the well, around the boot, and holds moisture. I think the boot decays, gets electrically leaky and provides a lower resistance path to ground. The gap on the plugs is pretty wide, so a higher resistance. add to that the fact that the plugs had a bad habit of removing the threads from the aluminum head when the plug was removed, people (me) took the attitude, 'leave well enough alone' so the plug ran a 100,000 miles or more, so the gap was no doubt a bit wider than spec.
So, possibly not premature failure of the coil, per se, but it was far easier and less risky to replace the boot/coil assembly and be back on the road, instead of addressing the possible root cause. it fixed it and I was happy.
I frankly was terrified of messing with those plugs, especially the back ones because I am round of belly and short of arms and legs and getting to those back four plugs, on my F350 4x4 was a real chore! especially on the right side.
I am pretty sure neither the 1999 F250, or the 2000 F350 had plugs replaced for over 100k and both were running like new when the trucks rusted out from underneath me and was retired. If I was to have a complaint about ford trucks, it would be their sheet metal! You could hear them rusting as they left the factory!

This particular dealers' policy was to install coils WITH a plug, no exceptions . I informed them that the plugs/ boots had less than 12,000 miles on them so they gave me some slack, claimed 1 of the plugs (out of the 2 problem cylinders) had no electrode

The started building the 5.4 motor in 1997 i  believe... I had a 2001 and a 2002 .... in 2005 they modified the motor to be variable cam timing... that introduced additional problems... They built that motor till about 2012 i believe, about 15 year run...... Now they have  a 5.0 V8 based on the motor from years ago, and a 3.5 V6 dual turbo motor.... they also sell a smaller V6 and a bigger displacement V8 if you need it, but the 5.0 and the 3.5 are their main units.

YES... the VCT is variable cam timing.. There are two cams and two cam chaines, one for each bank.. The motor starts in a retarded position and as the rpm increases the  CAM TIMING is advanced... That is done with a small hydraulic piston in a bore actuated by motor oil pressure.... that is called the PHASER.   There is a screen that filters the oil as it goes into the piston bore.. OLD dirty oil can plug the screen... The PHASERs have also been known to STICK... The oil is turned ON and OFF by a small electric solenoid... and they have been known to fail..... if you get the PHASER code, problems can be any one of the above.

FORD had spark plugs that were TWO PIECES crimped together in 2005- 2006... some would SNAP when you tried to get them out.... That problem was fixed by 2007... Once the plugs are CHANGED to the new style, your good to go.

You should only use MOTORCRAFT plugs... they will last 100K miles... For some reason the 5.4 EATS anything else..