update on exhaust issues... can anyone help?

[Jaxonalden]

This is just my opinion. To do their job, your O2 sensors need to read the O2 levels. The sensors are different before and after the cats because the resistance will be different when reading the exhaust gases because of the temp of the re-burning of the hydrocarbons. That re-burning confirms (through the O2 sensor) that the engines computer has the correct air/fuel ratio for the current conditions. When the oxygen sensor fails (or in your case removed and not reading the O2 in the exhaust), the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to. It will also throw up a code to your computer saying "the O2 sensor is bad".
You wrote "The rear sensors I just plugged in and zip tied them up and out of the way". Those sensors aren't reading a thing! No wonder they threw a code.