I've owned my 2001 LS v8 since the beginning of summer and have just recently learned I should be using premium fuel in this engine. I've previously been using regular unleaded. The engine light has been on since the coolant hose blew off due to rotted plastic. I have the cooling system repaired and the engine runs and maintains itself properly. However, a few codes are still triggering the light - P0171, P0174, and P0300. These read System too lean Bank 1, System too lean Bank 2, and Random/Multiple Cylinder Misfire, respectively. After doing a bit of research into these codes, I read a few articles that suggest poor fuel quality could be causing the misfire, and following the misfire the unburned oxygen would trick the O2 sensors into thinking the system is drawing in too lean. Could this be linked to using the "lesser" regular unleaded fuel over the premium?