Newbie with demandated isx

[Cscolem]

Hey guys, I'm a bit in over my head. I'm a row crop farmer that has a few semis but we've always stuck with older one, preferably a big cam 350 Cummins. A good deal popped up and I jumped on it. 2013 freightliner day cab with an isx cummins. It was fairly cheap because the guy had caught some of the emissions stuff on a pole, and insurance deemed it a total loss rather than pay 20 grand to have it all redone. That guy bought the truck back from insurance, had it "demandated" and drove it for 2 more years. Flash forward to me, I test drove it and loved it. Seemed like it had gobs of power. Finally put a load behind it and gears 1-4 it pulls like a ox. But you get into the highway gears and its a dog, dumping black smoke. I bought a code reader just to see what would come up, and I got fault code 122. I download quick serve so when I get to work today I will go through the diagnostic procedure for that code. Turbo looks like they replaced it but left the old actuator. I wish there was a way to take off actuator without having the insite program. Can anyone give me a bit of help or is it time to call a professional?