The most common cause is the NSS Switch for that type of problem, yes. I gave a comment to:HagensborgViking a while back for just about the same issues you have now. Here is a copy of it, and this would apply to you as well if you choose to replace it.
The NSS (Neutral Safety Switch) itself is located on the driver side transmission. Their are a couple of things you need to know if you decide to this yourself, is to work on the plug-ins first. They can be a problem as GMs sealant used from the factory has been known to bond the plug-ins in place when heated. If this has occurred to yours, then you need to apply a source of heat to them (should be 2 plug-ins) to loosen them up enough to unplug them. Caution here, is just enough heat (not a direct flame) to loosen them up, not damage them (Hair dryer, or heat gun (from a distance)).
The next one is to make sure you hook the linkage up the same way it came off. If you hook it up the wrong way then the transmission won't shift into gears properly. This happened to me when I did my engine replacement (tired) and the sounds it gave off when selecting gears was gawd awful. Once I hooked the linkage up correctly, everything was fine and back to normal.
I apply a small amount of grease to the Manual Shaft which makes the new switch a bit easier to install. I also use Die-Electric grease on the plug-ins and seals to make that a bit easier to install as well and it helps prevent corrosion.
One last thing which I do on a regular bases, is to spray the outside wiring and shift cable at the NSS switch down with WD40. This keeps things lubricated and protected from the elements.
Here is link on the procedures for a 1996 model year. Yours "should" be the same as that, if not, let me know and I'll look it up at another source (but it should be):
http://www.autozone.com/az/cds/en_us/09 ... oPages.htm
PS: Just checked the books for your 2000 AWD, the switch and re & re procedures are the same as the 1996 information at autozone.
Hope this helps CDGsafari98. Please keep us updated, Thanks.