I think I located my vacuum leak!
I found the diaphragm that controls the coolant changeover at the transmission was not holding.
After capping the valve, the vacuum readings went from -8 to -19 at 800 rpm idle.
Is -19 a good value?
Hoping this fixes my codes once and for all!
Also - Will it take time for the PCM to relearn Fuel Trim, etc after the battery was reconnected?
Thanks!