thanks rednek. I am open to ANY suggestion as i am not sure if what im seeing is normal. my RPM's at 60 are inbetween 1500 and 2000 i know that at 75 im right at 2000. during both tanks the truck was empty 95% of the time, when it wasnt... it was pulling an enclosed trailer but only for about 20 miles per tank. and it was ALL freeway and it was only 1 time per tank.
I will check and possibly change my air and fuel filters as they have not been changed for about 5 to 10,000 miles.