02 Windstar LX poor gas mileage?

17 city and 23 highway would be the best you can get. That is if the vehicle is not loaded and is driven the speed limit. Expect less with a full load and driving over the speed limit. If your check engine light is on suspect a defective Oxygen Sensor. That is a prime suspect when the mileage suffers. If the check engine light is not on, I would suspect you may need to replace the spark plugs and wires on this vehicle especially if it has over 75,000 miles on the odometer. Make sure the tires a inflated to the correct pressure as listed on the driver's door post or in the owner's manual. Make sure to replace the Air Filter every 30,000 miles.