[Rick Parker]

As mentioned previously this is a very damaging condition if allowed to continue. I too recently notice the reduction to 91 at the pumps does anyone have an explanation of why? Fortunatly
the are a couple of Union 76 pumps at selected stations have 100 octane unleaded. Check the heat range on your plugs, go one step colder if your ignition will accept it and you might put in a fuel system cleaner in the fuel in a attempt to rid the combustion chambers of any deposits from an overly rich condition. They will form carbon and somtimes continue to glow and cause what you are experiencing. good luck

Rick