84 B2000 carb cleaner?

[84-B2G-SD]

Hello,
I am new to this forum (and any for that matter) so thanks for having me.
I am also new to Mazda B-series trucks... I am the new owner of a 1984 B2000 Sundowner
56K miles
original everything

runs good. original owner was a mechanic who really took good care of it.
It hasnt been driven in a few years, so I got it tuned up (plugs, dist., wires, air cleaner, fluids changed) plus got a new water temp sensor and a new muffler.

Its stalling out when its idling while its still cold. I know how to properly start it as well, but Im not sure if its the choke or the idle speed setting.

Also, Im thinking a good carb cleaning is due. Do those fuel additives really work? How about the spray in kind? Im willing to try them, but Ive read that the fuel additives can be unsafe for the cat-converter.

Also, it runs great from 0 to 55 mph. The temp gauge stays at about 3/4 of the way up. From 55 to 65, the temp gauge slowly rises up to JUST the underside of the upper temp line (but still within it). I think it may be the thermostat, but not sure. maybe the water pump? Or maybe this is within the normal range of operating temps? As soon as I get back down to 50 mph or below, the temp gauge goes back down to where it was.

An ideas?

Any help would be appreciaited.