sounds like you are doing just what I did, I can't remember the exact chain of events. but to answer your question about the meat thermometer; after i had changed everything it became a hunch to me that the gauge was shot, so i took the meat therm. that i have always kept in my vent blower (another story) and i placed it at several points on the engine, then i put it in the radiator wile it was running and while it was reading damb near in the red and it never got over 180 on the meat therm. and that is what the new thermostat was set for. so then i just got a new aftermarket temp gauge, that has its own sending unit and it also checked out right at 180.

hope for your sake this is your problem too. have you changed your water pump? i think you said you did 2 years ago, not that it should matter. I have had a pump from napa go out (bearings) in less than a year, that one totaly messed up my old 22re on my 4runner. I don't know of a story of a water that just stopped working, usually they leak or fall apart and make a mess. autozone or someplace like it sell easy to install aftermarked gauges that you could pop in your engine and see if this is your problem, you don't even need to mount it to check.

good luck