How's your air filter? I would think a clean air filter couldn't hurt. I've heard what Boost is talking about, that running the air pressure a little high will help mpg a little but I've also heard the trade off will be ride and maybe handling. I have a 2000 4x4 5.3 as well. I did a little math, this is just estimation, but for my ride, if the 91 grade was 20 cents more per gallon than the 85 it was pretty much a break even point. Assuming a 1 mpg increase, which is what I was told to expect, my price per mile was about the same for the 85 as the 91, so, if the 95 was less than 20 cents more than the 85 it would be cheaper, if the 91 is more than 20 cents per gallon than the 85 it would cost more, hope that made sense. I think the real secret is driving habits, stuff we already know, consistant speeds, lighter foot, etc. I don't think anbody will argue that 55 will get you better mpg than 75 but who can stand to drive 55? I took off my roof rack cross bars, more for appearance than anything else although I suppose it might reduce the wind resistance a fraction and give me 1/100 of a mpg increase, who knows.
Good luck
