1983 380sec fails smog - too rich

[gsr355]

I have a 1983 380sec that failed california smog as a gross polluter. The car is off the charts in terms of HC and CO (about 10 times max allowable readings), and Nox at nearly zero. The car has also has slight miss at idle. The car starts just fine when cold or warm and does run good, but feels like it is lacking some power. Things I've check so far is control fuel pressure, which is at about 3.4 bar. With the car fully warm, the on/off ratio is fluctuating between 6-7% which indicates something is wrong, since it should be around 45-50%. I've exchange the oxygen sensor for a new one, and tried to adjusting the CO mixture, but the duty cycle reading does not change. I know for a fact that the vacuum advance on the distributor is not working, but I don't think it will affect the reading that much. What are some of the things I should check that can cause a car to run rich all the time. I'm going to check to make sure the cold start valve is not stuck open all the time tomorrow. Just need more ideas on what to check. Thanks for any help in advance.