Lean Idle After Warm Up
 

Hello everyone.
My single cam KA has an issue where it will idle fine until it hits an exact point on the temp gauge, just past the middle of the gauge. After the needle hits this point, there is a sucking sound coming from the intake manifold, and the AFR goes to 17-18. When the happens, the car lopes and doesn't idle smooth (as I'd expect with this AFR). I have tried looking for vacuum leaks in the engine bay and have replaced clamps and resealed the IACV. I also blocked off the AAC valve thing on the side of the intake manifold. I can't figure out this issue, and hope that one of you guys have experienced the same problem or what it could be.
Thanks

Anyone have any ideas?

vacuum leak

Likely a vacuum leak. Think about it this way, you're saving on fuel though.

not sure how the SOHC's are, but I found a huge vacuum leak from one of the metal vacuum lines coming off the throttle body on my DE recently. I had a plug there and it must have popped off under boost. I found it when I did a boost leak test using a bottle of soaping water. Fixing that and dialing in the ignition timing really stabilized the idle speed and AFR's.

Just some food for thought. Good luck.