Nope, it's the opposite. There should be no vacuum signal at idle. Just off idle the vacuum advance nipple gets vacuum as the throttle plates open. If it happened your way, you would have vacuum retard, not advance.
Nope, but that is what I used to think also, the vacuum should be highest at idle.
A lean fuel charge burns slower so you need more spark advance, which is what happens when you have a lot of vacuum.
THere is no vacuum advance at WOT only at idle or cruising.
