1989 Ford Taurus MPG?

[Jordy]

I have a 1989 Ford Taurus GL 3.0L Vulcan, so about 140 Horsepower brand new and 160 Torque, with a 4 speed Automatic with an Over Drive. It has 92'500 miles on it, and climbing since its my car I drive to high school, and all around town. I recently did a tune up on it. I changed the spark plugs, to platinum ones, good for 75'000 miles. New Rotor, fuel filter, I cleaned the air filter, a KNN one by the way, and ran fuel injector cleaner in it in mid August or 2009. I put Lucas Fuel Injector cleaner in it always. I also, around mid October of 2009, disabled the fuel system, and had help from my auto shop teacher to hook up a can of injector cleaner to the car, so that's all the car ran on. I recently, about 3 weeks ago, put another thing of lucas fuel injector cleaner in the car. What I do is I put the cleaner in, at the gas station, right before I fill the tank, completely. I did the mileage, and I had got around 14 MPG. 50 miles of that was on the freeway, 70 MPH. Not very much was from warming up, and the rest was in town mileage. My sister did some driving, and yes shes a bit hard on the pedal, but nothing way out of whack, uses the pedal a bit more than me and she only drove it for maybe 20 miles, out of the total 145.1 that I got on this tank. The rest I did. I wouldn't say I drive like a granny, but I don't drive like a bad out of hell either. I could learn to take off from stops a bit easier, but I just drive the car the way it should be I think. Is there anything else I can do to increase my mileage?