Need help poor fuel milage

Replaced EGR in OCT. had them hook computer up to check everything checks out good only thing they see and looking into is that who ever rebuilt the motor last year before I bought the truck is that the might of put in the wrong injectors. I might have to have them replaced and if im going to dish out that much I might have the EGR system deleted.

 

I have replaced everything from manifold to manifold on it and no leaks checked with soapy water.

 

I will try to take a video this week to show what the truck is doing as far as speed and boost 70mph I'm running about 1500 rpm and 30 pounds of boost weighing 70,000

 

This is frustrating still getting poor fuel mileage had the gearing changed in the computer now getting only 4.2-4.6n ( injectors are the correct ones ) ran with a few guys that had 4:11 and 3:90 they have been getting 5.5 - 6 same year make and model and motor only difference was trannys couple had 13 speeds and the others had 15 speeds I have a 18 only thing I haven't done yet is to put it on a dyno and have them plug the computer in it to see WTF is going on.

 

Had the truck in the shop for 4 days trying to figure this out still only getting 4.3 - 4.6 mpg with a flattop sleeper hauling flatbed. even took a mechanic for a ride loaded and YES the turbo pressure is correct pulling a hard hill computer showed 53 PSI all parameters are correct in the computer.

Computer Showed
Over Speed 1
Top Gear 85%
Avg Speed Top Gear 70.3 mph
Avg Fuel Mileage 4.5 mpg

His words to me " Best thing you can do is EGR DELETE program but you didn't hear that from me. "

I have tried 2 of the egr disable chips on the motor and all it dose is lower turbo pressure power and fuel mileage to 3.8 in both cases.

 

I'm at my wits end with this I have replace EVERYTHING on the egr side Delta sensor, EGR valve, V Pod, EGR cooler all egr lines and sensors replaced. Had the system pressure tested no leaks overhead done fuel system checked for suction of air into the fuel system swapped out the 4:33's for 3:73's NOTHING HAS WORKED to increase the fuel mileage still 4.3 to 4.8mpg.