Scan your engine for codes. Cross A& B with a paper clip and turn the key on. If there are any codes other than 12 then come back to the site and and look under obd1 for your code. The codes are sent by the service engine light blinking. 1- 3 times 2-3 times means code 12 and so on. Also replace your fuel filter and check your air filter as well. One of hte tell tale signs of poor gas mileage is the computer screwing up due to a bad sensor or soemthing similar.