Ok I was actually going to post about my red hot catalytic converter. After doing several searches on here i found that most everyone agreed to much unburnt fuel. Looking at the reasons for unburnt fuel the one that surprised me is the temp sensor. I have a new one but was out of time to putting it on i will do it tomorrow. But i would like to understand how a bad temp sensor can cause you to run rich.

 

Cold start needs richer mixture. If temp sensor is incorrectly reporting cold temperature while engine is actually at operating temp, computer will respond by adding fuel that is not required.

 

Oh ok that makes sense.