I agree, the rotten-egg smell comes from the sulfur in the gas. It is possible that you might have gotten a bad batch. Has it been stinky for a couple of tanks now? You don't have a small leak before the cat do you?


"4X4 in upper case is $X$" Quoted from http://4crawler.com/4Runner.shtml
'00 tacoma 4WD---Sold to Toyota
'93 pickup 2WD
'85 pickup 4WD