I have a 1994 lumina Z34 3.4 DOHC. Ever since the car backfired the car stalls at higher RPMS or at idle when the car is at running tempature. the starts fine and is drivable but the car will choke out and stall if pressed to hard on the accelerator. i pulled computer codes and found 32 codes (PROBLEMS) With the car. Can it be a plugged catalytic covertor? a bad sensor? somthing pop somwhere? any ideas please help thanks