ok, i knew i needed to change my fuel filter, so i did when i got home from work on thurs morning. but i went back to houston, and my hwy mileage was still 15-16.5. that is bad for me. i am used to running them hwy miles at around 19-21mpg. does anybody know what might be my problem. i have 265/70/17's on it, but it was doing fine 2 months ago. all of a sudden within the last month, my mileage has dropped. i am driving the same, and using the same fuel at all the same places. what is going on? do you think it is the injectors? i know that my diablo will do diagnostics on them, but i dont know exactly how to read all of that. it is still under warranty, 91,200miles.

My guess would be the injectors, is it smoking at all? Mine started smoking and using more fuel when the injectors started going bad.

Is it time for an air filter change?

no smoking, unless of course i give it the pedal, and i get my normal black smoke. and air filter is a true flow. i might need to clean it, but i wouldnt think that would cause it to drop that bad would it?

I'd clean the air filter first.

will do, thanks