Change the O2's and i think that would fix it because most of the time when it's dead the car will stall so maybe it's just on the way out. If that doesn't work check the idle/air control system, if it's plugged up and sticky it's going to slow the car down significantly and i do believe that would make the sputtering happen as well. Anyone feel free to correct me if im wrong, but thats my .02

--brandon