i changed my sparkplugs and wires and put a new filter in it also and still

all i know is i have a 12 gallon tank i keep it fulland getting less than 200miles on a fulltank it has gradually gone down getting worse over time i changed the air filter only keep tire pressure right engine light is not on and just passed deq after doing a drive cycle

Years ago, I had a full size Buick wagon with similar mileage.Well maintained,ran fine,but mileage slowly became very poor. After I sold it,I realized that the culprit may have been a worn timing chain and sprockets.

12 gallons seems a tad small for this particular vehicle, my information tells me it should be closer to a 16 gallon capacity. Depending on how you are calculating your actual fuel mileage, this would obviously make it appear to be getting even worse mileage than you say now. One more thing I can think of off the top of my head would be a dirty mass airflow (MAF) sensor. This sensor is used by the PCM to control the amount of fuel delivered under many operating conditions. If this sensor is dirty or skewed out of specification, your fuel mileage can suffer. Realistically with this vehicle, your best bet would be to take it in to a qualified and competent repair facility. The technician will be able to look over the scan data, ( basically be able to see what the computer is seeing ), and make a determination as to why it appears to be getting such poor fuel mileage. Good luck, hope you get your mileage back soon.

I've owned many Taurus cars-all have a 16 gallon tank.

WHAT KIND OF MIIAGE WAS YOU GEETING FROM YOUR TAURUS