Hi what is the best way to check if IAC valve is set correctly
I don't know if it's the 'best' way but, I take the throttle body off the car. There's a couple of small cross-headed screws that retain the mechanism. When loosened they permit a small degree of rotation. Ideally the mechanism should be in the middle of that range.
It's a good opportunity to clean it out by opening it up. Remove the gasket if you're going to use carb cleaner on it - it will make the gasket swell. Then you can lubricate and make sure the cylinder rotates freely.
There is a 'how to' on the IAC valve.
With the throttle body on the bench, it's a good time to give it a thorough cleaning too.
Has it been off? Is there a reason to suspect it is changed?
If not, and the car isn't idling well, it could be stuck. Carolyn's advice applies