Walter, My mechanic told me that a red muffer is a starved engine indicating that the car is not getting enough gas. Since the car has been setting I would recommend that you drain the tank, and replace all the composites in the tank. The rubber gets old and starts to detorate, getting tiny rubber pieces throughout the system. Check the fuel filter. I had black rubber pieces in the filter. The black rubber plugged my injectors. If your injectors are plugged, I recommend replacing them. We tried to flush the injectors, twice at a cost of $104.00. The injectors are only $30 to 35 a piece for a total cost of $180 plus shipping. Mine were $180+$104 :) I replaced all the composites in my gas tank, the fuel filter, the accumulator, and the injectors and I haven't had anymore fuel related problems since. Check the fuel system and make the repairs necessary before you start changing the setting on the carborator. I didn't need any other changes after I flushed the fuel system. Dale