stinky exhaust

After driving the car the exhaust smell like rotten eggs . I have changed the catylitic converter and oxy senser because the car failed aircare with high HC and CO . now the readings are very low with the new cat . But after a run at high speed it stinks when I stop at a traffic light.
I assume the stink is because the cat cannot keep up with the rich mixture .Car runs perfect otherwise. Are there any common places to troubleshoot on this thing? :banghead:

on my 91 when the voltage regulator went bad it was charging the battery at 18volts and boiling it I would start the car and check to see if its over charging the battery might be yer source of bad egg smell

Give the cat some time to break in. It should clear up.