O sensor knowledge?

My area began emission testing last year. The car passed with flying colors. Yesterday it passed again, but the results were very different
this year....mainly the CO%.
The standard is 1.20: High RPM last year was 0.01, this year 1.08. Low RPM was up from 0.03 to 0.13.
The HC was a bit different too:
standard is 220: last year at High RPM the reading was 45 and 47 at low RPM. This year 17 at High and 100 at Low
The other test results are similar to last years results. This emissions testing is a new ballgame for me, so I'm at a loss to know what these results are pointing to?
During a 4500 trip last fall I had to use 10% ethenol gas for a few tankfulls. My mileage dropped almost 3mpg and when I got home I had a code, O sensor 'not ready'. I cleared that code and it's not showed up since.
I pamperwell-maintain this car as it's my get-out-of-town ride. My F100 is daily drive ride.
The Texas Clean Air website points to the sensor having a problem. My OBD had the sensor code, but it hasn't returned, so?
The car passed but I'd feel better about being closer to the first years result than yesterdays results. Any info would be appreciated. Thank you....
Dave S(Texas)
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