I recently got my DIYPNP installed and my idle is very high - 3000 RPM. This is my setup and what I've done so far:

setup:
The system is on an NA 96/97 miata
using MTX-L
I am using the 9697 3.31a tune
I'm using 3.31a firmware
I've set base timing with 10BTDC and am now running the ignition table
Idle set screw in same position as when working with original ECU (900-1000 rpm)


symptoms:
engine starts and runs smoothly (but at 3000 rpm)
AFR at 14.7
vac reads at 25KPA at 3000 RPM



After searching here and plenty of googling I don't have any idea how to diagnose this - any tips?

- How can I test the IAC valve?
- How can I test if there is a vacuum leak?

 

I noticed that under Idle control, my valve mode was "Inverted" on the base-tune from MsExtra and switched it to Normal - the car idles at 950 now and seems to run quite well...

Where does everyone keep this at (normal vs inverted)? And for the sake of clarity, what do you guys set for valve frequency?