ok i have a 97 jimmy with the 4.3 and an auto and we were driving in my friends 00 s10 zr2 with a 4.3 and a 5 speed and my jimmy out accelerates his buy a big gap he hits the gas and it accelerates like a Geo metro (i am not joking it really sucks) and he gets 300km to a tank of gas and he drives all high way where i can get 400km to a tank of gas on all highway

so is this just the truck or do you think something is wrong

also i have the newer 4.3 so the motors are identical

 

Your friend's truck has a problem.