I have a Speed Demon on an Airgap but never had the problems you describe just a blown power valve that took me too long to figure out.
My four mixture screws are just one turn out and the Idle Eze is open 1.5 turns, the baseline setting.
My fuel level is just below middle on the sight glass.
Do you have an open plenum, I use a one inch four hole spacer, makes throttle response really crisp ?
Can you really trust that A/F meter ?
Idle Eze Notes.