2003 Escape xls Poor gas milage

I have a 2003 escape xls with 138k on it. My gas milage is down to about 17mpg. I drive about 90% highway and 10% city driving. I have changed the oil, gas/fuel filters and spark plugs. Nothing seems to be helping. I have noticed that the transmission has been shifting differently than when I bought the suv with 90k on it. I have had it to two differnt transmission shops both telling me that there is nothing wrong with the tranny. That there is something wrong with one of the sensors or computer. Nothing else seems to be wrong with the vehicle.
Could one of these sensors be messing with my mpg? I have replaced the IAC valve for other reasons. This did nothing for the mpg.
Do the tornado air filters really work? I have heard how those air filters will increase mpg.
Any help would be greatly appreciated!

Mark

Try cleaning your throttle body with throttle body cleaner. Done wonders for my Five Hundred.
Franco

Also clean the Massive Air Flow (MAF) with CRC MAF sensor cleaner, and replace the upstream H02 sensor.