I did this job a couple of days ago. I found a pretty good good write up somewhere on the internet a week or two ago, but unfortunately I didn't bookmark it and my printout doesn't show it.
I removed the air box and ducting, then laid the throttle body piece down while still connected to its two coolant hoses. Then I removed the wiper mechanism and cowl piece, which was glued in place on mine.
I wiped clean the ends of the hoses as I disconnected them and marked them with black marker (yes, it is visible) to show where they attach. I forgot to do one and it was a bit difficult to figure out which end was which, so it is useful to save time.
The intake manifold is held on with four Allen head screws and two nuts on studs. You will need a long reach 5mm Allen wrench (not ball end - the screws are really tight) or Allen socket. The nuts require a 10mm socket.
There is also a bracket on either side of the manifold at the back. The one by the air intake is not too bad, but the one on the other side (right side of van) is really tough. A very useful tool for me was a 3 x 5" mirror. These brackets have 12mm hex head screws.
I dropped the attaching screw on the right side bracket when reinstalling, and of course it never hit the ground, but got caught up in the works somewhere. I normally would search it out or replace it, but considering how difficult it is to get at, and that the manifold seems quite solid anyway, I am not going to bother with it. I am not going to drive on rough roads much.
Unfortunately the spark plugs, although dirty, were not the problem, rather a symptom of a different problem.
