Ford Repair: Poor Gas Mileage/engine performance., poor fuel economy, mass air flow sensor

Question
I have a 1993 Ford Thunderbird with a V6 3.8 in it that has about  125,000 miles on it. I have been getting really bad gas mileage lately.(last tank was about 10 miles to the gallon) Not sure if these are related but it also seems sluggish in responding to my pressing the accelerator and doesn't seem to have the power that it should. Also if I put my car in drive after it has been running it idles very high, about 2500 RPM. And finally on rare occasions if I have been driving and then make a short stop when I come out and start it again idles very roughly until I put in drive and gun it a little bit.

Thanks for any advice you can give me as to what the possible causes may be.

Answer
I don't have a service manual for this vehicle; my manuals only go back to 1994 for the Thunderbird.  You should change your spark plugs if they are worn-out; and air filter if it is dirty.  These items would cause poor fuel economy and poor idle quality.  The intermittent high idle may be caused by a sticking throttle plate and/or bad throttle position sensor.  Your Mass Air Flow Sensor could also be bad.  

I hope this helps,
Dave