Alright, I got a more sophisticated ODB-II reader. I borrowed it from my brother. I was able to get more advanced diagnostic information as I was driving the car. I took a reading of “normal” sensor data. It shows the engine RPM, the mass air flow, and the output from the 1st and 2nd oxygen sensors. At the time this capture was made, the car was going from about 65mph to a dead stop.
The second capture was taking within a minute or so of the check engine light coming on. I’m going approximately 65mph thru the duration of the entire graph.