That is odd, I would have thought a turbocharged 2.0L would have more low end torque than a N/A 3.6L. I know that is one issue many had with the 3.6L when we went wheeling in high altitudes like Moab. It wasn't that bad in my Jeep since it was a Rubicon and all Rubicons have 4.10 gears standard, but it was noticeable in the Sahara which had a had 3.73 gears and definitely in the Sport which come with a 3.21 rear gear standard. Driving the Sport version on the highway at high elevation was the worst. Going from 50 to 60 mph took forever.
Not a lot of people know about the rear gear differences between the models and it makes a huge difference on the trail and on the highway.