Wow, what a difference a little basic maintenance makes!
So I pulled the Mass Air Flow (MAF) sensor and cleaned it. I also pulled the throttle body and cleaned it, it was pretty dirty. After reassembly, I mistakenly left off the vacuum line. Took me a few days to figure out why it was throwing air codes! Anyway, once I put it back on, the errors vanished.
I received brand new Iridium IX spark plugs and replaced those.
Like a brand new car! Zippy, responsive, and even sounds better!
So between the cleaning and the plugs, it made a huge difference in performance. Mileage is great, too.