the sulfur smell, rotten egg smell, is from the cat working hard. May or may not be the problem. It is something to check. The smell is from the cat overworking. Did anyone check to see if your engine was running rich or lean? Did they do a back pressure test on the exhaust system? (before and after the cat)
Is anyone sure that the cat or plugged exhaust is the reason for the stall?
Check your fuel pressure. make sure the security
light is not coming on. I would hook it up to a scanner and see what codes might be stored in all the modules.