My truck now, is a 2017 RAM 2500 CC LB 4x4 with the 6.4 Hemi and 3.73 gears. I bought this truck with 45k miles, it now has 55k miles. I tow a 2,700 lb 8x16 enclosed trailer with about 1,000 lbs of cargo. At 3,000 feet above sea level the truck is running in 3rd gear at 70 mph on the flat, it will run in 4th sometimes. No check engine lights. Truck engine feels like its running smooth and trans shifts smooth as well. I just moved 500 miles and used said trailer. I know this is a gas truck and it doesn't have loads of power, BUT, I am thinking there is possibly something wrong. Another scenario, pulling a hill with said trailer (3700 lbs) on a 5% grade at 5,000 ft above sea level, truck shifts into 2nd gear at ~65 mph and still cant hold speed. Is this normal? I had a tailwind wind pushing most of the way and still managed to get 5.5 mpg ( I cant imagine if a head a headwind, LOL). Empty I get around 11 MPG. Max towing is 12,500 and I feel strongly that if I had a even an 8,000 lb trailer, it would not pull it.