Re-post of edited DualSportDad;

know we spoke briefly earlier but this thread is lacking some information that I'm sure some will find helpful.

Downstream O2 sensors seem to be known as having their only duty to be monitoring the efficiency of a cat converter. While this is a main function it also has a function that allows it to protect the cat and prolong its life. It does this by setting a goal voltage for the upstream O2 sensor. That goal voltage is the target a/f at closed loop. In this case the vehicle is is trying to achieve that goal then when it comes to idle it takes some sort of equation and compares the current upstream O2 data to the downstream O2 data to verify the current goal voltage being set by the downstream is the correct value.

If the engine is running smooth, no poor idle and no flat spots during acceleration then you can usually narrow it down to the converter area. I have seen small pin holes in a cat cause these codes and what is much more common, down stream O2 sensors plugged into the wrong banks. It is possible that the ECU is performing the equation incorrectly but that is a last resort repair as that is impossible to know for sure. To me it sounds like your O2 sensors are plugged into the wrong banks because you have not mentioned any driveability problems. I have seen people gut cats and then install spark plug non-foulers into the down stream O2 sensors to get the down stream O2 out of the exhaust enough to keep the check engine light off for having no cat. While it keeps the light off it changes the upstream goal voltage to a point the vehicle runs pretty bad. Even a pin hole in a cat can have this affect. But if the O2 sensors are plugged into a fairly healthy engine with cats that are working properly but in the wrong banks it will still well enough but fail the test the ecu performs because it's likely one cat is worn more than the other and there is a very narrow margin for the spec the ECU is looking for.

Good luck, hopefully swapping the connectors for the down stream o2's solves all your woes with the car.
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Does this reference voltage "goal voltage" function of the downstream sensor only occur during closed loop?