1. Order the real deal NGK Platinums (unless your year Xterra requires the NGK Iridium), as they are not too expensive.
Got the best deal from these guys... Car ID
$8.95 each, and through the chat feature, the guy gave me an extra 5% off. Just man up and do it, don't chance it.
2. Buy this from Harbor Freight. 9 pc. wobble socket extension set.
You'll also need a ratchet, 10mm and 12mm sockets, 2 flathead screwdrivers, coffee, and a winning smile.
3. Do it WITHOUT removing the plenum, if you X is older like mine is.
Remove the long black intake thingy between the radiator and the engine, and remove the cool looking "4.0" cover from atop the engine.
Now... I had originally planned on removing the plenum... UNTIL one of the throttle body's hex head bolts stripped out on me. DRAT! Heck, it's a 2005 so it's been there a while! No big deal, I thought, I'll just keep the throttle body attached and disconnect the hoses and make it work. Until I couldn't get the hoses disconnected. Again... 13 year old hoses, not coming off, and I didn't want to replace them, I needed the job done that day. And I didn't want to disturb the vacuum hoses that I'd need to disconnect, so I was stuck with doing the job with the plenum intact. With all those old hoses, don't chance it, boys and girls. It's easy enough to do with the plenum intact.
4. The hardest part for me, something that I wasn't warned about beforehand... those darn CLIPS!!!
These things is hateful on an older X.
The driver's side clip were easy, lots of room there, you see. But disconnecting the passenger side clips were NOT easy.
Here's a trick for you... insert the end of a flathead screwdriver between the black coil and the gray hateful connector. While holding it there, use another flathead screwdriver to press down on the end of the gray connector lever (I had to use a good amount of force). The connector level will "pop" down, when it does, quickly rotate the other screwdriver to separate the connector from the coil. This may be the only good way of going about this. See pic!
5. Disconnect this hose.
It was nearly hard as a rock and not easy to move, I twisted it back and forth with pliers (GENTLY NOW) until it came off.
This was not my photo... so thanks to whosever it is!
6. After unscrewing and de-clipping... carefully remove the coils.
Up and out for the rear and middle, and up and *towards the front of the engine* for the front one. The boot will flex, you'll be fine.
7. Do your plugs AS you remove the coils, one at a time.
So that you don't drop anything down the holes.
8. Reinstall the middle coil AFTER you get the front one done.
More room that way, trust me.
9. Use flathead screwdrivers to push the clips back in.
10. Stand on something to get high enough.
The X sits a little high, I stood on my spare time.
So there you go. Not too hard, just takes time. Hope this helps someone!