2008 Ford Explorer - gets stuck in 3rd gear

Hello, I have a 2008 Ford Explorer automatic. Recently I have notice that it feels forced, when on higher speeds than 45 it appears as it is not shifting up, I kind of gets stuck in 3rd and it will go like that no matter if I go up to 80mph, also even at this higher speeds I don’t see the rpms go over 3k. It will be under those but it feels like it’s stuck on a lower shift than it should. I have not notice overheating thou. And also you can hear the engine kind of working forced since it’s not shifting up. If I slow down it will shift down with no issues, and start to shift up as I accelerate but once it is like in 3rd I believe it will not shift up anymore.