For rear leaf bushings try
http://www.independent4x.com they carry poly bushings for most Isuzu stuff. I got a full kit for my 86 trooper and the shackle bushings matched an old set I had laying around for a luv. I didn't have any way to check the front spring hanger bushings, but they looked like they should fit.
On the other stuff,
http://www.rockauto.com does have upper control arm kits, and stabilzer bar bushings/end link kits. They might have some of the other stuff as well.
On the emissions hardware. It would pay to test some of this stuff out. The thermal vac valve for example either opens or it doesn't. If you can blow air through it cold its bad, if you can't blow air through it with the motor at operating temp its also bad. The mixture control valve has a test procedure in the shop manual that I don't recall off hand, but I could look it up for you. Some of these items are going to be very hard to find as aftermarket replacements, so you'll be either be using junkyard pulls that may or may not work or you will be paying a large sum to get them from a dealership. (If that is even possible)
If you really have trouble tracking stuff down that you need, you might try St. Charles Isuzu. They have a very good rep over at 4x4wire.com for being able to get parts and giving a square deal. You can find contact info for them at
this link
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diffently thats going to be a junkyard part 