Lonestar CM871 MPG

[Lonestar10]

Hi all trying to coax more MPG out of this pig of a truck.
2010 Lonestar - CM871/EGR/DPF - 13sp - Tripac APU - 1025000Miles 150k on overhaul and DPF replacement, 90k on new turbo/actuator, 500HP Cummins stock tune 2017 March update with DOC DPF TSB CPL reprogram
Computer says 3.36 Gears in insite, dealer said 3.55 "72MPH 1450-1475rpmish", seems to be regening every 100-150miles, pulling flatbed 70-78k lbs.

Running flatbed i cant really slow down and baby it i'm running regional making next day deliveries and reloads.

Bought the truck 1 month ago.
What i'm getting - 4.5-4.7MPG
Speeds i've tried running - 67-72 fuel mileage doesn't change in that range.

Things i've done - "All cummins parts" new IMAP/Exhaust Backpressure/EGR delta.
I have insite and couldn't get a lifetime fuel mileage it said 32mpg "i wish" i dont know if this is because i have the information center where the big cubby usually is or not as my trip mpg in dash reads 0.0 and instant trip fuel mileage is reading all sorts of weird numbers.

Sometime soon i plan on getting an overhead done as i don't know the status since it was overhauled.

I have yet to get the full egr tuneup done as i just became an owner-op from company driver and truck down time after all the cash i spent to jump into this is a short term pipe dream.

ied like to see what i can pull out of it before delving into "tuning" or maybe i have to before i can do better i dunno. my fathers doing the same thing with a 2007 T600 with a CM870 getting 5.5-6 with no tuning.

So as i said i have Insite working but only have cal-term stuck at the pc-id stuff to activate it.

Any help you all could offer would be wonderful. and thank you Rawze i think ive watched every youtube video youve made feel much better about owning a longnose....prostar ;>

also regens are 3.5-4.0 in/hg in the history with 520-570/900-1150/1050-1100 temps i did a forced regen with insite and got a .8 in/hg in history.

also runs the same on all 6 cyls while doing a cyl cutout running 1 at a time.