Ok, I did it finally, and I'm glad I did. The plugs were OEM from 2000, and they looked it too. The electrode was worn down and the plugs just looked tired. What a pain though to get to the plugs, I put NGK platinums in it and I will be changing them now every 60,ooo miles with the timing belt. Ugggg I'm sore from doing that job.

 

So it's as tedious as the instructions show?

Did you notice the car run better?

 

The biggest pain is a few small items, like the EGR tube bolts that are very difficult to get to (big hands), and then the plug wires themselves were a pain to pull out after 10 years. Also take your time when bolting down the manifold, it was really hard to get the gasket to line up. It is tedious and will take about 3 hours, and while the manifold is off tighten the valve cover bolts, mine were loose causing oil leaks.
The Monty runs better now, I notice a bit more "pep" while driving it. I'll see how the gas mileage goes here over the next few weeks. Oh the plugs had 114000 miles on them too.

 

I just replaced mine plugs and wires.
Did you replace the manifold gasket?
Did you use the OEM wires?
I replaced mine when the rig was at 61,000 (first change), now I'm at 107,000.
Like you said there is a noticeable difference in the performance.
I drive my Monty pretty hard about 25% of the time, so I slightly lean towards the "severe" service suggestion in the FSM.

Good on 'ya for the DIY!

 

I bought a new intake gasket but re-used the EGR gasket, as I did not have one. Next on my list is to drain and flush the tranny and do a brake bleed. My next major servicing at 170,000 miles will be a new timing belt, water pump, cam seals, spark plugs, belts and such.
Yeah I left the stock wires in, but next plug change it will get new wires.

 

Man, kudos to the DIY'ers on this job. It is a b*tch. I've pulled the plenum off twice on my 3.8. My FSM calls for Iridium plugs, and I found out the last time someone did the job they put in platinums. After 50k, they were worn down to the nub.
I reused the plenum gasket both times, but the tricky part is getting the damn thing to lay flat and seated in the exact same spot after it's been used. It curls up pretty good and without some way of keeping it flat, you're sure to ruin it or reassemble without a proper seal.
My solution to that; I dabbed a very little amount of lithium grease on the mating surfaces on each end of the gasket and on the narrow surfaces between each intake hole on the lower plenum. Then, lined up the gasket perfectly by hand and pressed it on. The grease is tacky enough to hold it flat (when it's at room temp) yet won't allow the gasket to stick to the aluminum for future removal. If I remember correctly, I think the gasket has a poly or teflon coating on it too.

Also, something to keep in mind for next time:
I've read the screws that hold the butterfly valves have been known to fail/come loose. If one of those entered the chamber, it would be a disaster! I didn't think to check them last I was in there, but making sure they're tight is some very cheap insurance, especially while you're in there.