As Rowdie says, a vacuum leak is still a good possibility. I am of the opinion that replacing the vacuum hoses and especially fittings is probably easier and faster than finding a leak. Often the issue is numerous tiny leaks from small line cracks and hardening rubber on connectors.


Also, even after cleaning, the ICV may not be closing down as much as it should. They do have a limited lifespan.

You can try clamping the large hose going to the ICV closed, which should drop the idle down to the point of almost killing the engine. If it does, your ICV isn't operating properly. If it doesn't, it's probably the vacuum leak(s).