So I have also had the service throttle control 4 times. First was @38,000ish, then @41,0000, then @44,000 (and somewhere inbetween. Dealer had the 2016 Big Horn for 2.5 weeks. First time, they replaced some parts and replaced the fuel filter; 1 injector; and 1 injector line.
The last time - a different dealer cleaned the Exhaust filter (free) and have had zero problems since. I currently do not use any additives, but will discuss with technician. My current solution is to reduce the oil change cycle to 9,0000 and change the fuel filter every other oil change. At the same time am adding a request to clean the exhaust filter for each visit.