Low RPM / Stuttering - Inconsistent

[fixkick]

all normal hot is 750 to 850 RPm spec.
cold varies by out door temp and for sure how cold the coolant is, at 150F the cold temps end and hot 800 arrives.
the lower RPM is the EGR main sticking open
as you come to a stop or just cut throttle to zero, (right foot) the EGR is command close, if it dont close rpm can go to 400RPM and engine misfires and shakes hard.
a very common thing, this,  EGR might be cleaned (main) to cure this, 50% change of success. if EGR is super old , chances less.

Im pretty sure this is it,  and not something far worse.  injectors leaking or crank pulley front falling off. is it loves to do latter.
good luck to  you !!!!

This problem isn't very consistent, I sense that when I've been driving the car for a while (at least 15-20 minutes and its very warmed up) the idling problem goes away.

^ I had the same, my problem's inconsistency was very much linked to outside temp and what speeds I was driving. Fine at 10C, not fine +5C - 0C or below 0C (Fine at 50F, not fine 41F - 32F or below).


I suggest getting IR gun to check the STAT housing to verify temps after driving say at least half a hour. I had similar issues with -91 Vitara G16a (Sidekick in US?).  My posts (1991 Vitara G16A frigid) but probably not worth reading all that b$.

My old STAT was open at all temps, fan clutch was semi sticking etc.

I replaced STAT, fan clutch and they helped a lot, but here at winter the car still over cools, so I blocked RAD with cardboard as I some times got CEL 13 due to to low temp and O2 sensor test failing.

After adding block for RAD those stuttering issues ended. (RPM going so low even RPM meter shows 0, but engine still manages to bounce back to idle). Anyways It's easiest to check the water temps before you go deeper into EGR and other stuff you need to dismantle.

As far as I can guess, if the temp too low ECU has problems guessing if it should use "choke" or not. And when you constantly linger on the borderline it causes problems (and high fuel consumption).

ps. Additional benefit, I can get the cabin hot now

that is correct, but the OP never told that outdoor temps were at (record in Sweden 1942 −20.6 °F) −29.2 °C in Orland.. ( not something easy do work with)
nor if the gauge for temp drops.
the EGR line G16 loves to stick. when old.. (and for sure hot when metals in it expand and are not equal (steel and aluminum( my 96 cleaned it like 4 times, and was good for say a month that fails again)
the EGR main has  a valve inside, that has shaft and the shaft packs in carbon and sticks, some can be cleaned but can be 1/2 effective,
he can also scan this Cars PCM using OBD2, if USA car,, and see if the thermostat never loses control once it is how, all USA cars, 1996 or newer we can do that, very easy, if no logger for tool , then 2 persons do that safely..
his car is Tracker and is not sold in EU, and only in Canada or Alaska would this get that cold here, in N.America's
The Trackers here were made in CAMI Canada plant. I owned 4wd version of his 96 here. I have scan data on it, too.. logs.
the 96 Trackers in USA, the P0117 /0118 will set if the thermostat goes nuts. here.. (only scanning for DTCs will find it and scanning for sure when RPM fails, too, is a win)
The 96 has clock timer inside that if it takes too long for the thermostat to go correct is sets the above code DTC, 150f is the threshold.. cold to hot.. in our cars.. (USA) remember OBD2 is a USA invention, and law here 1996 plus, no copied world wide.
The make the car under other names in canada too, Sun Runner is one, and more. So in truth Have no idea at all where OP lives nor in what country bought new.... Klondike to key-west FL, is huge. area.