Vacuum reading help.

When a engine is misfiring and/or not running smoothly any test instrument used will twitch. Years ago I tryed everything imaginable to correct a poor idle/run slant 6.
In the end a remand distributer was like dipping that car in the fountain of youth.
I must add that its poor run wasn't consistant. Sometimes it ran better or worse than other times. My guess is the point dwell was changing with distributer temperature.
Good luck with it.