i have a 97 rs and i have this same crap hapening .if i replace my plugs its is fine but in one day the plugs foul out again and its back to normal stumbling again. the plugs are white like theyve been way too hot. but why? i get code 31 also. ive reaplaced alot and still comes on.so i dissconnected every hose from the EVAP canister and blocked off the vacuum lines to it but still i get this prob. spark plugs fix it but foul out within a day. why is this? i get no other code// i am about to bust out my CAT to see if that could bo clogged and causing this but i am out of ideas. if would have never bought this car if i knew this would happen . only 82K on whole car from dealer. i dunno... help....