You have a marginal failure, and the cut points are actually quite generous. Likely cause is catalyst aging. It's not running hot enough to use all the O2. As catalysts age they need to operate at higher temperature to achieve peak reaction efficiency.

Check threads started by me over the years on M103 emissions diagnostics. Shorting the R16/1 resistor and plugging the vacuum advance signal line may help, especially if the high speed test is done first. The retarded spark advance will increase EGT and increase the temperature of the catalyst bed so it will use more of the available O2 to oxidize HC during the idle test.

If the catalyst is operating at peak efficiency, the O2 content should be zero to no more than 0.1 percent. At 0.6 percent for the idle speed test yours is leaving a lot on the table. The high speed no-load test yielded only 0.2 percent O2, and you can see that the HC is dramatically lower.

Make sure you warm the engine up thoroughly by putting as much load as you can on it on the way to the test station. Never shut off the engine prior to the test, and while waiting turn on the defroster, which will engage the compressor and keep revs at about 1500.

I go to the drive-through place at a time when I am either first in line or go right on into an empty test bay.

Duke