[mehlosTT]

Jeesh_ relax kids_ think horses not zebras when you hear the hoofbeats pounding close.
rear bank runs leaner and_ it has newer O2 sensor.
1st: when those O2 sensors start to go, they read richer then reality, so they lean the fuel out. The log suggests it is working okay as there aren't the O2 dips before going leaner ( correct?)
if so_ then when not under higher fuel psi, she runs leaner. And it is not always exactly the same but fairly close each time.
Runs fine when she has more fuel psi like at boost? , as in when rpms are going to be above5000 or more can mean that when NOT under boost, the rear injector or all three even, can have some spray pattern irregularities_ minor clogging. But>..don't forget the obvious other factor.....a poor fuel pressure regulator that is not maintaining enough fuel psi is letting too much fuel by- pass back to the tank, coupled with less then perfect spray injectors..well?
Try this before going nuts with new parts_ one can of really good Injector cleaner that doesn't leave future residual build up.
then get a nice new cheap OEM regulator unless you of course already have an adjustable regulator.....if so, try the injector cleaner first and check check check the O2 sensor's connector , specifically the green wire which is the O2signal wire's ground. Curious to see which thing was the culprit.