I just hit like 67k miles on my 4runner. it is a 4.0 V6, and it JUST started smelling like a rotten egg. Now are my cats bad or my O2 sensor? Or what? My mom also has a 4runner just like mine with 97K miles..and hers started at 90K miles. I need a solution for this because it stinks...literally! It only happens when you get onto the truck.