High HC need suggestions and experienced opinions

[KMinAF]

18 months ago at 130109
High speed HC 58 CO .15
Idle HC 62 CO 62

Last week at 134055
High speed HC 311 CO .85
Idle HC 470 CO .5

After replacing O2 sensor (which tested ok) and finding the bad plug wire (slight stumble at idle no miss under load)
High Speed HC 145 CO .65 PASS
Idle HC 266 CO .21 FAIL

The car sat for almost the entire year and what little I did drive was 90% freeway. Yesterday I replaced the spark plugs (which were brown and #5 showed signs of blow-by) and reset the timing from 14 to 10 (yes the diag connector was in place).

The car idles smooth as silk, accelerates with 8lbs of boost with no problem, there are no vacuum leaks and all management control parts are in place and functioning.

I did add some injector cleaner that I had laying around could this be a contributing factor? It was some cheap stuff from Checker Auto Parts.

Could the Cat Converter be failed? How would I check it's efficiency?

 

[Nick M]

Could the Cat Converter be failed? How would I check it's efficiency

It could. You check it by having an oxygen sensor behind it. If the voltage switches like the front sensor, the cat is no working. This is how OBD II cars know whether or not you have a cat in place that works.

After replacing O2 sensor (which tested ok) and finding the bad plug wire (slight stumble at idle no miss under load)
High Speed HC 145 CO .65 PASS
Idle HC 266 CO .21 FAIL

Stock airflow meter and injectors? No performance mods? If you have a slight exhast leak, the oxygen sensor will read a false lean, and will richen the mixture. I say this because you say the car drives fine and idles good.

 

[KMinAF]

3500 miles since engine was rebuilt. Only mods are 3" exhuast, boost control valve, K&N type air filter and Cometic head gasket. I am concerned by the drastic change since the last test.