Cleaning the iacv too much can damage it. Its a zeolite bearing surface and if the impregnated oils are washed away it will wear out very quick. Which manifests itself as unstable idle speed.
Also make sure that the air manifold under the main intake manifold is correctly connected, it has supply lines for different vacuum valves that control idle speed under different loads.
It connects to the ac idle up valve and also the power steering load sensing vacuum valve.
Make sure the throttle body has its correct gasket when installing otherwise you may end up with sludgy engine as pcv wont work due to fresh air vent being blocked or have unstable rpm if its wrongly sealing.
(Im a bit oldschool and break out my vacuum gauge to check the idle vacuum and it has never failed me)
