Renegade Slows Down on the way up Loveland Pass

This is the second time I've run into this issue. Yesterday I was driving up Loveland pass, near the top on the west side going east and my Jeep began to slow down, I'm literally flooring it. I had this problem a few months back and replaced the air filter and spark plugs. Well now I just got a rooftop tent that weighs like 80 lbs, so I'm wondering if the extra weight is causing that. Yesterday it was probably around 70 degrees or so, so it's not like it was crazy hot. Anyone have any ideas what's going on?

 

If you are at elevation, your engine might be starved for oxygen. I'm assuming you have the 2.4L?

 

Yes, I'm assuming they faster I go, the more likely this is to happen as well?

 

With the rooftop tent, it's more likely the extra drag/frontal area then the extra weight, but both would have an effect.