Ford Repair: Gas Problems on 1997 for winstar, e 85 fuel, temp guage

Question
Last week i filled my tank. did 179 miles and had to put in 16 gals too fill it again.. Since Wednesday i put 79 miles my tank was toped off full.. Now I'm at 1/2 a tank..Where's the gas going?
I have checked all over, no leaks and i don't smell any gas.
I don't think some one is steeling my gas... what could be the problem???  example: I'd be doing 200 miles for a full 20 gal tank.. something is not right... Hope you can help? Thanks..

Answer
there is a lot of variables so it will need to be checked out-

first make sure temp guage is reading about middle when hot you vehicle doesn't have a choke per say it operates off of coolant temp so if your thermostat sticks open or opens to soon you will notice a reduction in fuel mileage which is very noticeable-if your area has already switched to e-10 or e-85 fuel your mileage will drop some with e10 and alot with e85 and really nothing can be done about this-other things leaking injector/s-burnt plugs-bad o2 sensor/s-dirty maf sensor/restricted air filter-low pressure in tires-the list goes on-have it checked by reputable garage and once you find your problem switch to a good synthetic oil like mobile one extended or amsoil either will help mileage some and although expensive will pay for itself with increased fuel mileage and longer intervals between changes.