105k miles on a 97 EX and the gas mileage is around 20mpg. Even though thats not bad i know that it is capable of way better. I recenlty changed the spark plugs due to a "cylinder 4 misfire" CEL and the downstream o2 sensor becuase apparently that went bad. but my mileage still suffers. btw i dont drive like a maniac (shift under 3k). should i clean the EGR valves (saw that in another thread)? or anything else anyone thinks.

 

air filter is a good cheap next step ... make sure you don't just pop the cover off and look at the top of it, the bottom is the dirty part