Changed out the wrong O2 sensor and like magic, the four bad sensor codes are gone. Now, as I expected, the only codes I am getting are for catalyst performance below specs. This is because they have nothing inside (I'd bet money.)

Moral of this story - All O2 sensors are not created equal, regardless of what my Independent Tech says. I'm sure he would have eventually found the problem, after taking $1600 of my money for a new computer that would not have solved anything. I wonder if the dealer would have know?

PLAY IT SMART - ALWAYS RESEARCH THE PROBLEM YOURSELF!!!! DO NOT TAKE ANYONE'S WORD FOR IT BEFORE YOU DO.

This forum is probably the most valuable tool in any quest for MB knowledge, I don't know what I would do without it. Thanks to all.