2014 6.7 surging issue

[Black6.7]

I have a 2014 6.7 Cummins. At steady throttle, between 1500-2000 rpm, and under light load(going uphill usually), I can very noticeable feel it surge and watch my boost gauge and rpms fluctuate. I've had the issue since I bought the truck a little over a year ago. I've had it in the shop for several recalls and had them look at the surging issue each time it's been there. I've had the same answer, that they couldn't find anything wrong, every time. My truck will be out of warranty this coming year so I'm trying to figure out how to resolve this issue before then. Any help would be greatly appreciated!