Idle issue on an 89 sidekick 8v

[fixkick]

your IAC is bad, time to test in in a pan of wot water.
150F it closes. fully
that assumes you thermostat in your car is 180F or higher, and actually works
yes,. me too, id not give up on it, 30 years is young if you do the work.... nobody does that, just us, and good luck to you !!!!