Potential EGR delete problem

[Bewil83]

Just bought a deleted 2019 Pete with an X15 Cummins a couple months ago. It was hard to tell while bobtailing. But as soon as I hooked to a trailer and started down the road, I noticed my fuel mileage was junk at only about 5 miles to the gallon with an empty trailer cruise set on about 68-70. I then noticed when I started pulling a slight grade even with an empty trailer, it felt sluggish. I checked my manifold, pressure gauge, and it will not go above about 20. I first covered what I thought were the basics as far as changing the filters (including oil, fuel, and air) and this made zero difference in the performance overall. I’m planning on putting the truck in the shop this week to try to put a finger on what’s going on with it as I’m now fairly certain there’s a problem in the delete somewhere. However, last week I started noticing what appears to be exhaust rising from somewhere below the fan blade. I haven’t been able to get far enough under the truck to see where it’s coming from but I’m wondering two things. One can an exhaust leak cause my loss of power and poor fuel economy and two could that be something done on the mechanical side of the delete it’s causing the exhaust problem? Or could my problem be something different altogether? Any feedback would be appreciated as it’s difficult shooting in the dark trying to fix a problem.

Thanks!