It's still too rich.

Because of the excess fuel the engine is continuing to run after you close off the throttle ... btw you also have a bit of an air leak too!

That extra fuel is mixing with air that is getting by which is what is keeping the engine running.

A faster idle should NOT affect the engine in flight however, something else is amiss too...

Make sure you check the tuning completely and perform pinch tests and nose up/down pinch tests too!