Idle issue on an 89 sidekick 8v

[Freaky Beanie]

https://photos.app.goo.gl/NRCT1fBYSGAR4PoR7
Here are the temps. IAS thermostat and Radiator. I monitored the temps and the thermostat is functioning correctly.

why wreck the calibration , first.
first prove what is wrong, then hack it.
these TB are rare so needs extra care to now what is wrong.
the thermostat needs to be at 180first
the water flow true the IAC body must not be restricted in any way.
if all that is ok, the IAC is bad, hack away.

I'd have in in hot water, 150f and see if it closes, if it is only a bit off, turn the ring inward so it just hits the piston and no further, the test at 150f again, and repeat until it is right.
that is how to calibrate it, if you want to know..
guessing will mess up the calibration and the ECU will not like that, it knows the actions of the IAC and injects fuel based on a model of those actions. (cold)
cold to 150f and then its offline. the IAC.
hope that helps..... good luck