My 88 I4 has a inconsistent high rev then almost stall that usually happens twice before, 1. It returns to a steady idle, 2. It stalls. It usually fixes itself tho.

The only thing consistent about it is it never does it on the initial start after it has been sitting for awhile, and the entire time its driving it has no issues.
However if you start it again 15 minutes later it either fires up without issue or does the almost stall again. It will do it randomly until its been left to sit for awhile. Never has an issue driving tho.

I tried to do some research and I came to the conclusion that the IAC might need replaced, so I did and it took about 4 starts, before it did it again.
It was worse this time though, it didn't fix itself after 2 cycles it just kept on doing it.
I also can't drive it right now so I can't really reset it via the driving method. Currently rebuilding the calipers since they are such a PITA to find and I ended up accidently tearing the new o ring for the ebrake screw so I need to wait for another rebuild kit to show up. I have the proper tool to rotate the piston in as well.

Im not quite sure what it is at this point because I rebuilt the tbi, cleaned it out with throttle body cleaner when it was outside of the engine, new tps, fuel regulator, fuel injector, fuel filter, new icm, coil packs, sparkplug wires, guy before me changed the fuel pump, new air filter, and I think thats it. Other than that I did replace the pressure switch and tcc solenoid, but I don't think that is relevant to my issue.

So I'm just lost, if anyone knows what it could be, I'd appreciate the response

It also doesn't have a high or abnormal low idle, bounces between 800 and 1k.