Genaro, I think I've read your posts on this before but have forgotten what else you did to try to solve this. There was something about the notion that all the b23f cars have a flat spot, but the one I recall discussing is the single knock that occurs when you stand on it at idle.

What part of the acceleration curve does the flat spot disturb? Is it like mid throttle and 2500 rpm? Full throttle and 2000 rpm? Or is it like fuel starving at full throttle and 4000?

The adjustment located on the air mass meter is for idle mixture trimming, as I think you know, and not really related to the adjustment of the AMM function at all. There are also some factory adjustments that are made to the amplifier in the air mass meter assembly, but they are made to center the response curve of mass airflow to voltage output rather than shape the curve, as you would want to do to program out a flat spot. These adjustments are made with a laser on the ceramic plate where the amplifier chip is located.

I had two b23f cars to play with, but the only flat spot I can relate to is that one right off of idle that appears to be the knock and resulting ignition timing adjustment.
--
Art Benstein near Baltimore