vacuum gauge to solve idle issue

Lantern battery may have the volts, but no amps.That choke sucks power, that the lantern battery may not be able to supply.
-cranking the housing only changes how soon the choke comes on/off.
-adjusting the choke pull-off(vacuum-break) sets the A/F at start-up, and throughout the warm-up period.
-Make sure the timing is stable, at ONE fixed value, whatever it is.
-make sure the fast-idle cam is correctly set; usually on the second highest step.You don't want the engine reving too high during the warm-up period, and if the rpm is too far out of spec. it messes with the T-port sync, causing you to want to mess with the mixture screws.This would then cause the screws to be out after the engine warms up. No! Don't do it! The A/F during the warm-up is set with the position of the choke blade.
So,as you may have figured out, The T-port sync on a warmed up engine, is somewhat critical. It will set the baseline A/F under many operating conditions. If it is out, you will have warm-up issues. If you solve the warm up issues with a bad T-port sync, then you will have issues in the standard mode.