Tune help needed

[KDub9]

Sorry this is probably a big-time Noob question. I need some help on what steps I should take to properly tune my cm871. I purchased a truck that was already mandated. Probably not the best decision but it was just freshly overhauled. Oil ran clean for about the first 3000 miles then went Pitch Black.
From what I gathered there is some software that I need to download in order to extract files from my ECM and also a piece of Hardware that I will probably need to plug in with.
Any details would be greatly appreciated.
I'm getting about four and a half miles per gallon and I've been pretty easy on her too. I know there could be many other underlying issues but I feel like a tune is a step in the right direction.
On behalf of my wife my boys and myself I want to thank you for any advice on this subject , it truly can have a deep impact on all of our lives. Thank you in advance.

[Waterloo]

First, where do you live?

And, you can do this yourself if you want, I did mine in the driveway a few years ago with some help from Unilever and Rawze...

You will need one of these... https://www.ebay.com/itm/Cummins-INLINE-...SwIJlZ9U~7

And a laptop, preferably running Windows 7. Windows 10 will work, but the Windows operating system is missing a few items that will need to be downloaded from MicroSoft to make the Insite software work. Nialo helped me with this issue at Rawze's house when we loaded a fresh copy of Insite and the other software on my MacBook Air in my Windows partition. And yes, if you own a Mac you can run a copy of Windows on it and Insite.

You should get the above no matter what, you will need this for any future diagnostics.

PM me your email and I will send you the instructions on how to do this if you want. It was not that difficult on the CM-871.

[KDub9]

Thank you for the response! I will send you a pm.

[Waterloo]

Check your email!