At 100k, I'd change the differential fluids too. Front and rear.
Forget what Ford says about using synthetic oil in the rear diff, but non-synthetic in the front...That's the most assinine thing I'd ever heard. I use a full-synthetic 75w140 gear oil in both pumpkins, and it's working great.
As for the rest...I think you've got it covered. I did my 100k a little early, but it included changing fluid in the transmission, transfer case, both differentials, and power steering unit, changing the fuel filter, tranny filter, spark plugs and wires. My air filter gets looked at regularly and gets changed as need be. I haven't done the PCV valve. Mine is working fine still. One of these days I'll probably change it "just to do it". I also cleaned the throttle body and MAF sensor with a spray air intake cleaner. This really seemed to help the idle...It was a little rough before doing this, but after, it idles smooth as glass.
They say changing the brake fluid is a good practice, and I can't say I disagree...I did a brake fluid flush on my Grand Prix switching it out to DOT 4 fluid which has a higher boiling point, and it really made a difference in the pedal feel. Much more responsive and less mushy. One of these days when I have extra time and a free hoist, I'll probably do this on the Explorer too. I've never been totally satisfied with the feel of the brakes on this vehicle, so every little bit that can improve things is something I want to do.
