4.6L 2V Spark Plug Change Advice
 

2006 F-150 RWD Scab ~47,000 miles.

I've been having, IMO, a sort of moaning or slight vibration around 2100-2200 RPM when the engine is under load. This is in all gears and very slightly when revving it in neutral.
We're pulling 6000+ lb travel trailer across the country and it's not a big deal, but it does get annoying sometimes.
I had it on for an oil change about a week ago. They couldn't find any problems in the drivetrain from the transmission onward or with the motor mounts. They said a tune up may help.
I asked what that entailed and the mechanic said the first stage was just a spark plug replacement. After that it would be exhaust/airflow analysis.

I figured spark plug replacement would be easy enough although my only experience with that is on aircooled VWs.

Some quick searching about it showed me some horror stories of broken plugs and different torque values.

I looked a little more on this forum and it looks like my year and engine may be spared all that.

I would just like to ask here, what is the current conventional wisdom on changing spark plugs on the 4.6L 2V as I don't have a tech manual:

1. Do I indeed have the 4.6L 2V with my 2006?
2. Which plugs? Other threads indicate the OEM Motorcraft SP413 or Motorcraft platinum SP493. I'm partial to NGK, but I'll stick with experience from others. Would I benefit from platinum (or other performance plugs) for the towing that I am doing?
3. What is the proper torque value for the plugs?
4. What is proper gap setting?
5. Which tools will I need?
6. It seems the rear-most plugs are a pain to get at. Any special tools or techniques I should know about to make that easier?
7. Anything else I should inspect while I'm digging around in there? Anything that could save me trouble down the road?

Thanks in advance!

Sounds odd but I had similar experience with 2001 4.6 and after pulling alternator and getting tested during replacement it was found to be good. While I had no leakage at the time I found it was the water pump growling when under acceleration that put strain on serpentine belt. I changed the water pump and all noise went away. Never did leak but bearing were going bad.