X15 Power/Noise

[DDT LLC]

So recently bought a 2019 w9 to add to my fleet and it has a cummins x15 performance series with a 18 speed. My issue is from the day i first hooked a load to it the truck dont seem to run right its tune and deleted from previous owner so its got a knock under load so checked and double checked overheade and gear train. over head good but the cam adjustable idler gear was tight with the cam gear so reset backlash. Next time out still had a knock like before just not as bad but ran with my computer plugged in and found high exhaust pressure and high boost 45psi ish so looked into turbo found it was bad replaced and then retested truck has better power still not where is should be and back pressure is lower (170-179 under load now) also now im running higher coolant temp 200-230 and oil temp 210-240 also i noticed when in the top 4 gears if you push throttle down to half or so i get a motor change and light vibration on the floor but if im on and off a few times it clears up and runs back to its normal self another odd thing is the fan seems to have a mind of its own it comes on as it should when temp is high but at an idle it sometimes will just randomly turn on i love my ISX15 but this new style X15 is giving my a headache any help or direction would be extremely helpful thanks in advance oh and my fuel mileage tanked im loaded both directions and also no im driving a brick pushing the wind but before new turbo was 4.0-4.1 now after turbo 4.3-4.5 and my other trucks are around 5.1-5.5 and they are all bricks to lol