Smells like rotten eggs when engine is reved up

Most likely a contaminated catalytic converter would cause this. It could have gotten fouled by contaminated or leaded fuel, or motor oil or coolant getting into the combustion. A Kia or Mitsubishi technician would be familiar with your model car. If you want to find a Kia or specialist, here's our directory link for you: https://repairpal.com/kia-repair-in-philadelphia-pennsylvania