Multiple emissions codes and probably wrong calibration.

[Rilloroc]

Let me start by saying that I did not do the proper research before purchasing, or even soon after purchasing. I'm here now though. I have had multiple emission codes for the entire 9 months I've owned this truck. 2014 Kenworth T680 with 2013 ISX15 2350 rated at 400hp with a 13 spd, 454000 miles at time of purchase, 575000 miles now..
About a month after buying it, the light started coming on. I would stop to get it looked at and there would be multiple codes related to the DPF, but none would be showing active. I never saw a decrease in performance or mileage at this time. Averaged about 5.8 per gallon, which was much less than I expected. A couple of weeks later, in June of last year, it needed a parked regen and then derated a few hours later. I took it to Cummins in Amarillo where they scanned and saw the codes, looked it over and said it was way past time for a DPF system cleaning. 10 days and a high 4 figures later it was ready for pickup. Performance felt about the same to me but the fuel mileage increased to high 8's low 9's. 2 days later the codes came back but performance and fuel mileage were unaffected. Sometimes the lights on sometimes not. Nothing ever showing active when they scan it. Sometimes a "Derate in 3 hours" shows up on the screen, but only for a second or two. Then goes away. Occasionally it will show a different time limit. "8 hours", "27 minutes", but usually "3 hours". It never actually derates though. And again, that message only lasts a second or 2.
In November, I started noticing a loss in power. I immediately started to head back to town before I could get to far away. When I shut it down, that was it. It would start up like normal, run for about a second then die like it was starving. I had it towed to Summit Kenworth in Amarillo. After about 2 weeks they say the problem is the wiring harnesses, both engine and cab, and both fuse boxes. I okay the work and a week later, that's in and the truck still wont start. Another week and they say the turbo and actuator is bad. I okay the work and another 2 weeks and the price of a low mileage, used Cadillac later, it runs.
I immediately notice a loss of power and fuel mileage drops back down to about 5.6mpg. I stop by to ask whats the business and they say it just needs to break in a bit. i also start to notice a scream periodically when I approach 1500rpm. Not everytime, but sometimes I hear what I think is a belt scream and the engine pull some. The closest I can compare it to is when I used to have an old oldsmobile with a 305 in it. When the A/C clutch would engage, the motor would pull down and the belt would throw a fit. It feels and sounds kind of like that sometimes when I get up to 1500rpm. Not everytime, but most. It will scream until I let off the throttle then go back to normal, and I can proceed or even exceed 1500 without trouble. So that's going on and the lights are still coming on. I take it back to Cummins in Amarillo to see if I can have better luck back over there.
They say the codes are because the sensors related to the codes are bad, and replace all those sensors for another damned obscene 4 digit number. No difference. 2 days later codes are back and the brought some of their friends. The new codes are occasionally showing active when scanned.
Last week I had enough, and decided to finally take my career serious. I read up and found this place. I picked up insite 7.6.2 and started poking around for myself. i notice that my dataplate on Quickserve doesn't match up with my dataplate on Insite. My engine, and quickserve show 400hp, ECM code EF10049. Insite is showing 475hp and EF10154.17.
4152,4151, and 3232 are the codes I've been getting for 9 months. The others are new arrivals. The truck has only asked for a regen twice in the 9 months and 120000 miles that I've owned it.
Any help would be appreciated, you may have to talk to me like I'm 2.
Rawze,I'm putting in the boost and pyro gauges Tuesday. Oil bypass also. Take it easy on me.

Edit: Let me add that I never took it anywhere asking to get power turned up or anything. Either it was like that when I bought it, or maybe Cummins or kenworth did it accidentally when I took it to them for repair.