When ever I do any aggressive driving, or step on the gas to go over 65 miles per hour to pass someone. , I get a sulfur smell. And sometimes It hesitates very subtley as I do it. Is it my catalytic converter? I am still under warranty, so would it be covered? I do not get any light to signal a malfunction or anything or check engine light. I would like to get any repairs done now, while the warranty is still good..