08 yz450f bog

I have a yz450f that will either bog or shut off when I blip the throttle in neutral, sometimes if I downshift and match rpm it will bog too. Other then that the bike seems to run pretty good. It’s my first dirt bike and first time riding one so I don’t know too much yet. i got the bike used from a one owner who always took good care of it very particular about maintenance so I’m hoping nothing too serious is going on. I asked a few buddy’s and they said it could be a carb adjustment but I’m really hoping it’s not a valve adjustment? I’m also running 91 for now till I can get my hands on 95 not sure if it matters just putting it out there. Any suggestions would be great!