Chevrolet Repair: 01 suburban brakes, chevy suburban, gas mileage

Question
I recently noticed a decrease in gas mileage on my suburban, Which I use mostly for towing. The front brakes have a really bad drag, I changed out the rotors and calipers with heavy duty upgrade brakes for towing hoping that would help with the drag, but it didn't get any better.Midas told me that gm has had problems with the brale lines and that I should replace the stock lines with stainless lines. I personally think it is the mastercylinder.Any help would be appreciated.

                thanks shane later

2001 chevy suburban 2500 4x4
8.1 liter 45,000 miles.

Answer
if you are noticing a constant drag on the front brakes, the calipers are not disengaging fully. i would check for a partially collapsed brake line. as far as i know, gm never had a problem with their steel brake lines. are you losing any brake fluid? if not, you need to track the system for the blockage.