Idle Won't Come Down

[warrior84]

I have a 1990 300zxtt with ~63,000 miles on it. It's a 5 speed manual. I've had the car for about 9 months. 8 of those months it was in pieces (long story). During that time I deleted a lot of stuff and replaced just about all the vacuum lines and hoses I could. It now runs smooth and boosts 10 PSI.

The problem: it idles 1600-2500 rpm

Adjusting the IACV adjustment screw does increase/decrease idle, but with the AAC unplugged it will only drop to 1600 RPM (it is all the way in now. I've turned the screw in and out several times to try to loosen things up)

The TPS is within spec on the different measurements per https://z32.wikispaces.com/Throttle+Position+Sensor

I ohmed out the various idle components:
AAC 10.x ohms
Air Regulator ~76 ohms
FICD ~24 ohms

During the downtime I had the plenum off and replaced the gaskets for the IACV and Air Regulator

Turning the AC on lowers the RPMs down to around 1500-1600

I cleaned the throttle bodies and set them

Any ideas on what I'm missing? Is it time to just start replacing sensors/solenoids?

[JJT211]

Have you checked your ignition timing?

[AZhitman]

IACV only affects idle at operating temperature, until the fast idle valve is warmed up.

Air regulator (next to IACV) commonly fails in the open or closed position (maybe open, in your case).

Remove regulator, and blow through it - if it is cold it should be open.

Applying power and ground to the terminals should shut the valve.