Holley/Demon Carb stumble

Good morning all,
I allow myself to give you an advice, very modest that my 35 years of experience in motors give me.
when you go to work on your: carburetor, ignition, valve adjustment, ... make notes in a notebook, it's really very important.
always only one change at a time,
each setting change must give a positive result, no change? be careful!
for the lambda probe, very important the location !!!
the choice of the location of the lambda probe must be to respect this operating temperature.
once again I apologize for my english. I only wanted to advise you to do the most meticulous work, and always with notes.
another very important point in my modest opinion:
always look for the real truth of the engine !! and not imagine in your head.
and always new spark plugs.
good race