Can't Pass emissions

[quote:bc579a1ea8="KenOfAZ"]I have a 1979 Toyota 4x4 pickup with the 20R four cyl engine. I can't pass emissions. I replaced plugs, rotor, cap. wires, pcv valve, and carburetor. I still couldn't pass. I took it to a repair place and they got it as close to passing as they could. They said it was borderline. It failed with about 20% more than allowed on the CO at cruising speed. It passed CO at idle easily, as well as passed HC easily at cruise and idle. The repair place said the only other thing they could do would be to rejet the carb and it would cost me $200 and they couldn't guarantee that it would improve or that they could find leaner jets to fit.
I am wondering if I could instal a universal fit (about $100) catalitic converter and improve my CO by about 20% at cruise speed. Or any other ideas?
Thanks for any help.[/quote:bc579a1ea8]

Could be an air pump or diverter problem and catalytic converter.

[quote:3a9abce5f7="rasmataz"][/quote:3a9abce5f7]

Could be an air pump or diverter problem and catalytic converter.[/quote]

The repair place tested the air pump and said it was working. I don't know what a diverter is. I would think they tested that too. It does NOT have a factory catalitic converter. I was thinking that if I added one, it would reduce the CO significantly. Am I right? Or would it barely make a difference in CO? I am thinking I could add a catalitic converter for half of what they want to rejet the carb.
Thanks.