Chevrolet Repair: 98 Silverado. Idling rough ,only when very warm out, rotten egg smell, pvc valve

Question
Hi Curtis
I have a 98 silverado 4x4ext cab, 5.7 R eng,aprox 173000KMS When it's cool in the am,it runs great,BUT in the afternoon when it's warm out and on my way home , it starts to run very rough at idle and under light load,the exhaust smell is not like raw gas,but like rotten egg ??? , I am sure that it is a sensor, but which one of the manny ??? ,air flow, oxygen sensor,or ??? three months ago it had a full tune up and service with all filters,air oil,gas,pvc valve and soforth.Any help that you can giv me would be greatly apreaceated.Thanks for your time  

Answer
Usually the rotten egg smell comes from the catylitic converter. If it was a sensor you would have an engine light on. If it's stock exhaust I would say that maybe your cat is clogged or you have a bad O2 sensor. As far as the way it runs when the temperature is different outside I would say that the MAF sensor may need to be replaced. This sensor lets the computer know if the air is cold or hot and how much air is flowing through the intake.