My 03 has had a decrease in gas mileage of 15% or more lately. I asked the dealer about "flashing the computer", they just blew me off.

Anyone had any experience with this sort of thing??

do u have any mods that u did lately

when that happens, I use fuel system cleaner to help rescue. I don't know if this would help you....worth a try.

Be sure that your air filter is clean. A dirty air filter will kill your MPG. Good luck!

Where do you live? You probably just got some oxiginated fuel or the fuel that you buy not contains more ethanol. Engine's not specificaly tunned to use ethanol bassed fuel will get worse gas miliage on them becasue of the extra oxygen content. (o2 sensor is correcting for the wrong stiocometric value now becasue of fuel change) What brand fuel do you buy? Ask the seller if there is ethanol in the fuel. If there is, you might be able to get you car tunned by a chip or at the dealer to use ethanol bassed fuel. This is popular in the midwest where corn bassed ethanol is plentyfull.