Engines misfire when lean, but not when rich. It's best to stay a little rich than a little lean.
I once figured out that if the idle mix is lean, the engine will tend to hang on the high side of idle as you coast to a stop. If it's rich, it'll bog a bit at a stop and then idle up to a stable rpm. If it's too lean, it'll struggle to stay running at idle...
I've used this on most of my motorcycles and several cars to excellent results.