Guidance requested for ISX

[BlueSpruce]

Hello!
A little history on my experience with this ISX. I purchased a 12 Pete 389 with a CM 2250, 2.5 years ago that was de-mandated by the previous owner. I haul crude oil in the oilfields of NE Utah. My loaded weight every day is 129000 pounds and the particular run I am on involves a 25 mile pull with grades from 2% to 8%. I was uniformed about the effects of modifications to the emissions system and the previous owner didn't inform me of previous issues he'd had. Within the first 6 months of ownership I had 2 head basket failures. After the second time and due to the advanced mileage of the engine, I went ahead and bought a Cummins certified reman engine in May of 2022. I also found out that the shop that did the original tune, before I purchased the truck, obviously didn't know what they were doing. When the engine was replaced, our shop manager linked via remote access to a buddy of his back east someplace and "adjusted" several parameters in the tune. When I got the truck back it definitely ran better and temperatures on the gauges were down and within acceptable limits, or so I thought. Fast forward to last week and again, after 85000 miles, have either cracked a head or lost another head gasket or liner. Shop hasn't diagnosed the failure yet so at this point I'm uncertain of exact problem. Coolant pressured up and sprayed the truck and after engine was shut off it hydro locked. Either way I now have no doubt the tune is causing the issue. Truck came from the factory with 565 hp, it was set at 600 before I purchased it. I'm more than willing to go back to the lower rating, but what I need most is as much reliability as possible.

So my request for help is this: can someone please message me with the exact items I need to purchase to access and download the tune file so I can send it to knowledgeable individuals who can help me make this thing reliable.

Thanks for any and all advice.