What's wrong with my Cummins ISX????

[Killbilly]

I've got a 2010 Kenworth W900L with a 09 ISX 450 in it. Since I've bought the truck it hasn't been the road yet and the truck has ran fine, started fine etc. Well the night before I was to leave in it it to lease it on to a company the feeder tube from the exhaust to the exhuast pressure sensor broke at the flaring on the exhaust manifold. I replaced it with one off of a core engine after cleaning it out. I started the truck to verify it was fixed and noticed the turbo was much louder the it had been previously and when I tried to give it throttle it wouldn't go past 1100 rpms and was blowing out the thickest of black smoke then back at idle it was smoking black but you wouldn't notice it unless you focused on it. Thinking the line I replaced had caused it I loosened it and not change, it was still running like crap. After several random start it was still the same. The morning after I tried again but this time it was blowing black smoke at an idle with no throttle response at all from the peddle but did eventually act as it did with the original issue. Well, thanks to the videos on YouTube I did the egr tuneup without replacing any sensors as the soot wasn't really that bad at all. I started it and again no change. I kept thinking about the load turbo whistle it idle and for giggles I unplugged the turbo actuator and restarted the truck... well I was able to get better throttle response, less black smoke and higher rpms then before (1200-1300) but at the max rpm it would run it would puke out black smoke but not nearly as much as before. I could really use some serious help with this to figure out what's wrong.