Today I got my truck inspected. I passed but my Hydrocarbons are pretty high and the Carbon Monoxide jumped up a good amount. I just did plugs about a week ago and cap, rotor, and wires within the past 6 months. I also replaced my o2 sensor about 3 weeks ago. Im not sure maybe my timing is off? My idle does seem to be rough at times not very consistant. Sometimes it will puff like a misfire. Any help would be great. Thank you.

Limits HC C0 NOx
1.60 40.0 2.50

Results 1.15 14.5 0.52

Last Years 0.62 2.7 0.56

 

If the catalytic converter is original, it may be worn out.