Are my o2 sensors starting to fail?

[Empty V]

So my car has lost a significant amount of power. When driving up hill it feels like the engine stutters. I'm guessing that it's not getting the proper fuel/air mixture. Has anyone experienced this?

It's an 01 QX4 2WD with 175K miles on it. I've never changed out the o2 sensors and figured they're on their last legs but I'm not a mechanic. Thanks for your help!

Billy

[Qxxx4]

are you pulling any codes? your service engine light should come on. Hook up a code reader from a friend or buy one and see if you get a code, that will tell you exactly whats wrong. I need to replace 2 sensors, but i dont notice any sputtering or performance being that bad.