Yes, there is something obviously wrong with the O2 reading. Air only has about 18 percent O2. The exhaust should have zero to a few tenths percent.

What kind of test was this? I/M 240? ASM? If NOx was measured it must be a loaded test. Can you briefly explain the procedure? Was there another set of numbers from a second test at different speed/load?

High NOx can be caused by lean, not rich mixtures, however, I don't think mixture is the problem. You need to do a thorough functional inspection/test of the EGR system - both the valve itself and the control system. It's not uncommon to have EGR system problems at this mileage on any car.

A dragging parking brake could cause high NOx because it places more load on the engine, but would probably not increase it this much.

Duke