After 5 weeks waiting for the def hose, I got my truck back. I checked fluids, Changed oil with Valvoline, dexos oil, and left on the 850 mile trip! Saw a tornado, 3" deep hail on road, fought severe winds etc. At times the colorado had a bad vibration. It seemed like an engine miss. It seemed to start as the tranny would downshift on a hill. Once I could feel a miss at idle while setting still at a fuel stop. 2/3 home it straightened out and ran fine for the remainder of the trip. I pulled a 900 Lb. 6' x 12' flatbed trailer empty on the way and loaded with a 2400 Lb. compact trailer and loader on the way back. Fuel economy was 25 MPG which I was very happy with. After getting home I checked fluid levels again, and coolant was low. It should not drop 2" in 850 miles. The intermittent vibration cause? Anti freeze getting into a cylnder? Transmission shudder? It almost seemed like a loud grinding noise. Noise was mostly when it was pulling hard. the noise/ vibration would stop as I got over the hilltop and the engine was no longer pulling hard. Engine temp stayed on the cool side. I checked tranny temp several times and never saw it over 200. It is a 2017 model with around 18,000 miles on it. I will call the service writer tomorrow. He was very good and in my corner through this ordeal.