Strange Idle Issue?

I have a strange problem where my car sometimes idles at completely different IAC positions when warmed up.

For example, this morning I started up the car and left it sitting until it was fully warmed up and idling fine, however the IAC was sitting at about 150.

I then drove a short distance up the road and stopped at a set of lights. Once the car found its idle again it was idling with the IAC at about 35 where I would like it.

WTF is going on here??

Looking at the logs, nothing has really changed. AFR is at about 0.97 lambda, IAT hasn't changed by more than 3 or 4 degrees, idle timing still around 16 degrees, same MAP, same RPM, etc.

I tend to think my throttle body may be slightly sticking or perhaps the IAC is playing up? Throttle body is a Fast 92mm.

Cheers
Benno

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