You seem to be indicating that your mixture is going lean when you step on the gas, rather than rich. Higher numbers are leaner than lower numbers. Do you mean the AFR goes below 13.2, or is it shooting up to 17 or 18?

If the needle is pegging at the high end of the scale, you might have a vacuum leak. A vacuum leak will also give an erratic idle, which can change with underhood and engine temperature. After you have checked every possible place on the induction and crankcase ventilation system for vacuum leaks, and repaired them, you can try adjusting the carbs.

I had a lot of problems with vacuum leaks on my engine: brass plug on the end of the intake manifold, rubber covers on the unused vacuum ports on the Mikunis cracked and leaking, rubber carb to manifold couplers not tight enough, etc.

My idle is currently around 12.5 or so, mixture goes up to around 14.5 to 15 when the throttle is first opened, then drops down to around 12.5 when cruising; probably too rich. My needles are at the richest setting right now, but the weather is getting colder so I will leave them be for a while. Idle speed varies with ambient temperature; consistently higher when in the low 40's or lower.

Performance is pretty good; fuel economy is so-so. I tried setting the idle mixture leaner, but the car runs much better with it at 12.5

Bill