I forgot the M110 was mechanical. I'm used to living in M117 K-Jet land.

The WUR is vacuum-based. If you have a vacuum leak somewhere (or your AAV is stuck open) the mixture will be richer than it needs to be. I assume you could test the AAV by taking it off the engine and trying to blow through it. If you can pass air through it, you know it's open.

Check that the idle stop screw isn't turned way in keeping the throttle propped open either.