Problem with my Chevy. Surprise, surprise...

Well my stupid Blazer has been running a little on the rough side lately but today, it got even worse with it not really wanting to stall but acting like it, it backfires and smells. Could this be the CAT? No CEL or anything. Ideas?

my tahoe was just doin the same thing we changed the plugs wires cap and rotor ...and my mechanic changed another part but for the life of me i can figure it out he said the truck must have been running rough there was some seriously bad arcing going on

So the tune up did the trick?

yea funny thing was we were on our way to dropping the gf car and then she started sputtering and backfiring she did it a few days earlier but thought she was good