Exhaust leak before the 02 sensor would give you high 02% and high CO.

Could have too much gas in the oil.

Measure the gases pre cat.

CO under 1.5%

HC under 350PPM

CO2 13.5 to 14.5%

02% .3 to .7%

Post cat

CO under .45%

HC 0 to 35ppm

C02 14.... Login to read more.