I have a 99 C5 that occassionally experiences a backfiring and hesitation while really getting into the throttle under hard acceleration. It makes a popping/snapping noise and the whole car bucks forward and back. You can stay in the throttle but it usually happens at about 4500 rpms. Also, while on cruise control, if you push the accel button on the cruise control lever it will hesitate also. I have just started experiencing this problem and no one seems to know how to fix it. I have a Fast LSX intake with fuel rails and no other mods to top or bottom end. I have aftermarket bolt ons like vortex air rammer, headers, etc. Anyone out there know what I am talking about? HELP!!