871 Horrible fuel milage

[Rockycoon75]

I have a 11 pete with a 485/1850 871 18 spd 3.55 rears getting horrible milage. I bought it about a month ago. It has 100k on a dealership overhaul. I did the egr tune up when I got it. New imap delta p and exhaust pressure sensor. Doser injector was previously replaced and was pretty clean. Truck isn't smoking at all and water temp is running between 180-190 oil temp 210-220. No codes no lights.
Over the last 2300 miles I'm getting 4.8. Half of the miles were empty
Doesn't seem to matter if I run 60 or 70 still sucking fuel. Power seems to be good.motors feels to run best smoothest between 1300-1650 under or over its feels a little rough almost like a miss. Usually holds 32 on manifold pressure. I have seen it pull 40+ several times and at times only pull 30. Not sure where to begin with it[/size]