Have sulfur smell and backfiring occuring could it be catalytic conv

Car has sulfur smell & dies when rounding corners or slowing down. It backfires, when restarting it sometimes. Car does also, jump forward sometimes when coming into a parking spot. It kind of sounds like it's running out of energy, when taking off(after "idling" sitting for a little while.) Replaced spark plugs, but no difference. Could it be the catalytic converter and/or EGR valve?

I'm trying to decide if I should drop more money into car or get a new/used one. It is an SE, 6cylinder,Automatic. In need of HELP!