Today I took my 85/240 wagon (193,000) to DEQ for another emission test. It failed.
About 5 months ago I had tested (it failed) and I didn't do anything about it until this morning. I gave the old report to my mechanic and he thought the catalytic converter needed replacing. But instead he tried the little stuff first - new spark plugs, air filter, oil change, adjust the timing (90$!! 65$ for 30 minutes of labor!).

Here is a comparison of the numbers from July/today:
THC (max = 2.00) 3.53/5.32 FAIL
NOx (max = 3.70) 10.47/7.94 FAIL
CO (max = 32.0) 21.9/28.1 PASS

other numbers (no standard/no max)
CO2 776.4/807.3
Fuel Use 10.79/10.18

Ok, the THC went up (is this some sort of drug test for my brick?), the NOx went down, and the CO went up (but it passed the CO test both times). No visible smoke and the car has run fine for over a year. Gas mileage a little low at about 21 mpg equal city/hwy driving.

Questions:

1. Do these numbers tell a story? Did my mechanic try to get it to pass by "any means necessary"? i.e., timing or sensors pushed to the limit?

2. Does it look like a "cat" problem? (mechanic says the one on the car is a "cheap one.")

3. Is there a test I can do for the "cat"?

Thanks for the help in advance.