Hello guys, I’ve never posted a question on a forum before, I’m in a screwed up situation. I was going down hill on i80 East into Reno in my 2017 3500HD 6.6L Duramax Diesel High Country DRW. I was pulling my 3 car trailer loaded with 3 units on it. I turned my exhaust brake on and pressed on the brake, the exhaust brake came on and RPM’s went up to about 3000, I took my foot off the brake pedal and continued down hill, my speed was slowly increasing so I put my foot back on the brake pedal, the Exhaust Brake went into the next stronger level, my RPM’s raised higher to 4000, then about 2 seconds later the Check Engine Light came on and a message came up in the little display, ( Reduced Engine Power ) then that message disappeared, another message came up, I don’t remember exactly what it said something like, ( Engine Cleaning Exhaust System Must Continue Driving ) pressed the brake pedal to slow down so my RPM’s would drop down. After that, the first message about Reduced Engine Power came back on and stayed on. Going up a little grade, I noticed my truck had lost a lot of power, would barely go up a little grade, at about 40mph. On the level freeway it’ll continue increasing speed no problem, but any little grade, and it’ll start to drop speed. Then slowly increases as the road levels out. Check Engine light stayed on after that, the Reduced Engine Power message would disappear sometimes and the Engine Cleaning Exhaust System Must Continue Driving would come up, as if both messages are connected with what’s going on with the truck. Can someone with some knowledge help me out please. Give me some advice on what I can do myself, or if I have to take it in. I really hate taking my truck to the shop. I have a hard time trusting repair shops, I’ve been screwed over a few times. Any advice that will help please, I’m supposed to take another load down on Monday, and I don’t know if it’s a good idea driving my truck with the Check Engine Light on and in this condition. Thank you everyone for and help. I would really appreciate it.