I have a 84 C10 with a 350, problem I am having is I cant pass smog due to blowing over 3 times the limit on CO. I pulled off plug wire one at a time and have 4 of them that have no change in motor when pulled off # 3,5,2,8. They are getting spark to the plug, I have replaced cap, rotor, plugs, plug wires, air filter, pcv valve, all vacuum lines, rebuilt carb, set timing, intake manifold gasket ( there was a small leak ) changed oil, changed coolant and put two new cats went for a re-test and no diff. Still no change when I pull the wires on the 4 cly. I am out of money and ideas, please help
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