running very rich please help

so i have been noticing that my car has been smelling like it has been running rich but yesterday i pull one of the plugs out just to check that and even the spark plug smelled like gas...like really strong. what can i do to make it not run so rich...as this is what is probably killing my gas milage. i only get 13.5 city and 16.5 highways. any help is greatly appreciated
 
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