Hesitation on Hills?

[KJ zGal]

So I've noticed within the last year or so my Jeep has gotten so it really hesitates and loses speed on hills...it's not really a big problem but it is kind of annoying when I have to down shift two gears or so to make it up hills it used to go up just fine. Any ideas what might be causing it?

 

[tjkj2002]

Tune up?

Cats starting to plug up?

 

[LibertyTC]

Has the throttle body every been cleaned?