I believe that the egg smell coming from my car from time to time might just mean I'm running rich. What could be the problem? Might it be a change in the weather?

 

egg smell is normally the sign of a failing catalytic converter.

 

That can be one indicator, but usually you'll see engine temps raise a little too.

PixelHarmony, if you aren't seeing the temps, it can be normal for a cat to emit that eggy (Sulfur) smell. Normally a nice long drive will heat up the cat and get it working cleanly again.

 

I might be the gas. Fill up with tank from a different gas station and see if the problems goes away.

 

Good idea.