What are the tell tale signs bottom end is too lean?

I'm not that experienced at tuning. After running a little rich to break in I started leaning out the HSN and it has great top end with smoke and good temps. When it idles the idle would be high then go low quickly indicating rich so I would lean the bottom, go for a run, repeat, lowering the idle gap as I leaned. What's the sweet spot? I figured if it idled slightly high after a run then settled 20-30s after that would be ok.

But, now my idle feels erratic up and down some times. Maybe I'm too lean now on the bottom?

Thx for the advice.

JJ