Idle, Runs good at startup, but idles bad after warm up. Options

[Raulm]

Three months ago my 1994 Celica started missing in first gear. The more gas I gave it, it felt like it was bogging down. It was also stuttering, and I thought I got some bad gas or too much ethanol in the car, so I got injector cleaner, put in some high octane gas, and it got a little better. Then it got worse again so I replaced my fuel pump, my fuel filter, my MAP sensor, my TPS, and my Cooling Temperature Sensor. I put a vacuum gauge on the EGR while the car was idling, and the car stalled out, which tells me the EGR is working ok. I removed the EGR, cleaned it, removed my throttle body and cleaned it, and it has improved. It accellerates fine without missing, it will miss so once in a while at high speed, but when idling it will miss, and it acts like it wants to shut down, but then it revvs up and it does this several times before actually shutting down. The only other thing that I am working on now is the IAC. I removed the IAC and tested it by applying 12 V to B+ and the ISCO and the little valve opened. Next, I applied voltage to B+ the ISCC and the valve went to close but did not fully close. After I removed the voltage, the valve went to a default position about midway/ half open. Is the IAC functioning properly when it does this?
I do not know what to try next if it is not the IAC. Please help.