good luck...
exact same issues I had... (well, some of them, I had a LOT)
I was in a VR 93 Acclaim wagon, the fukn overheating but not problem caused me lots of headaches.
it ISN'T the thermostat, don't get it replaced, you'll waste your money.
I'm guessing it drops back to normal temps after hitting op temp? like after 5-10mins driving? That's what mine did. and with the bloody stalling in reverse or while turning (which is what my pos did) holden cleaned my throttle body about 5 times and charged me for 3 of them, NEVER fixed the problem...)
as I said, good luck...