Welcome! Hard cranking, injectors maybe? Time to use that warranty and see what the dealer has to say. ETC is pretty popular around here unfortunately.
A few DEF sensors, but not even close to as many problems as the EcoDiesels. My brother has one.. 10K miles so far trouble free. But, all modern diesels are going to have emissions problems unfortunately.
If you want to get away from the EcoDiesel, how about the 2.8L Duramax? Decent size trucks, good fuel mileage as well... or you could always trade up and get into another EcoDiesel with a warranty if you really like the platform/truck.