Questioning 3-way catalytic converter?

What is your question?

Smell of "rotten eggs" & depleting gas mileage; (Down 10mpg) Is making me question a possible replacement of the catalytic converter? Also I am having problems clutch slipping with down shifts when I want de-accelerate to slow quickly or just before jumping RPMs & accelerating to pass another vehicle. These are the only times that I notice so far that the clutch slip is occurring. 1994 Acura Legend GS/LS COUPE 6-SPD MANUEL TRANSMISSION ;-)