after reading the instructions (owners manuel) it seems like gm has learned that we build or buy something first then read instructions later....checked the manual and sure as the sun comes up it says to run 91+ octane (premium fuel) did they "forget" to place this below the fuel gauge, or on the filler cap? I have owned several cars that required premium and all said it on the cluster. I drive a lot of miles and this will add up fast. Maybe this expains my consistant rough idle.
