I just got my 02 LS and the first time i filled it up, i used 87 octane gas - i quickly discovered this was a bad choice. the engine sputtered and the check engine light came on after a while, the engine code said the number 6 cylinder was misfiring. so i immediately ran the tank dry and put in 93 octane with Lucas injection cleaner and octane booster. after 2 tanks of this - the light went off and the engine didnt sputter, but it wasnt perfect. i put 93 octane fuel from racetrac in today and the check engine light came on again and sputtered a little bit - so back to the injection cleaner and octane booster...is this engine REALLY that sensitive to what gas is used or is there something else wrong?