Hey fellas,
I purchased my grandpa's old 1986 Toyota P/U after he passed away. I put seafoam in the gas, oil and intake. I ran the oil for approx 60 miles then changed it. I then changed the plugs, cap, rotor, wires and PCV valve. This was done last week.

I took it in for emissions today and it failed both CO and HC's at "high idle". It barely passed the idle readings. The HC was 235 (max 220) and my CO was 2.3 (max 1.20).

I went and bought a new Oxygen sensor and got it installed. Anything else that it could be?

Its a 22R (2barrel carb) with 75,000 miles on it.

 

A couple of things I thought I should add.
-It was driven 20 miles on the freeway prior to me getting the emissions done.
-It was purchased in CA (so it has the California emissions on it)


Do you think the Oxygen sensor could cause the CO to be high? Or is it something else?