That's a lot of miles, and I think high oil consumption may be the cause of your relatively high HC. The longer chain molecules in oil don't oxidize as readily as lighter gasoline molecules and the phosphorous in the ZDDP anti-wear additive is believed to accelerate catalyst aging.

I've got a summary sheet of all my emission tests going back to the first one in 1991. The results are pretty consistent ever since I did the R16/1 and vacuum advance mod for the '05 test relative to '03, and since that time my annual mileage has dropped from about 1500 to 500 per year.

My 190 should outlive me, and I already know of one guy waiting for me to keel over.

Duke