Does anyone know what a bad (or going bad) catalytic converter would throw for an error code? I am getting an erratic miss and check engine light on my 86 K-5. I already replaced the whole distributor and timed it properly. Drove around today, and it did it again. Seemed to miss/stall and then the check engine light came on and stayed on... Then I could smell the sulfur smell from the cat. I know that if your truck is running rich it will make the exhaust smell like this. Is there something else I can check, or does a bad cat cause a code 42? Could it be the mixture control sensor or TPS on the carb??? I did a search, but came up with nothing...other than replace the HEI module and pickup, which I already did. Also, was quoted 225 to replace the cat....does that sound expensive to anyone else but me???