At .8V means it is going into full enrichment due to WOT. At WOT, the system goes into Open Loop mode temporary which the computer does not compensate for the fuel trim until it goes back into Closed Loop.
I would say vacuum bleeding is mostly for speed. You gotta do the manual pump and hold method afterwards in order to remove the remaining air bubbles. It is a two step process.
BTW, Project Farm has demonstrated using an A/C vacuum pump with a mason jar. Seems to work well for those who don't...
Cases like this - you would really need to scope the #2 cylinder and try to duplicate the problem in order to pinpoint the root cause.
This is the event where the scope shines.
Which 2002 Jeep model is this?
Edit: From Owner's Manual:
Your engine is designed to meet all emissions regulations and provide excellent fuel economy and performance when using high quality unleaded gasoline having an octane rating of 87. The use of premium gasoline is not recommended. The...
Problem is these capacitance battery testers are not accurate at all.
Every time you test it, the results will change.
I got a TopDon and the results varies all the time.