need basic help on my 6.0

[HP=happypedal]

hi guys
got a 2002 1500HD gmc
4x4, 6.0, 4L80,

i think someone has been inside this ECU already.... (lot of IM READYNESS shows NA) it has always run well but gets only 12 mpg
i cant stand it anymore.
i only drive it for big camping trips so it sits a lot but now... im finally going to try and tune it up for some hyper millage highway land yacht status..... not gonna mob sand dunes or tow a boat.

can you please help me by posting a STOCK re flash tune, and, a good tune for millage?...

that way i have something to go off of... i will still play with the timing and maybe ignore an o2 sensor to try and get it to break 20MPG but.... it defiantly needs some brain help rn

thank you

[edcmat-l1]

You need to post your tune so we know what we're dealing with.

Or, you can go to the tune repository yourself and look for a stock file that matches your description.

[HP=happypedal]

can you link me?
i haven't even gotten my tuner in the mail yet. i want to hit the ground running

[edcmat-l1]

You need to have a customer page on the HPtuners site to be able to access the tune repository.