Ok, this what I've got... '87 TBI K5, 10b f/r, 3.42 gears, auburn in rear, 33" ProComp MT, 135k on entire setup, mostly stock, many sensors and wear items replaced in motor new intake, flow master exhaust..... how/what do I do to get a little more miles out this $$$$ gas? Could my pass side exzhaust manifold leak be helping? Any ideas? I drive fast all the time, but I used to get 13 at least doing the same stuff. Thanks for any help.