Engine is misfiring how to fix?

Hello,

When the engine misfires or have a faulty oxygen sensor, it typically creates a fault code and illuminates the check engine light.
Is you check engine light on?
If it is illuminated then scan for the trouble codes.

https://youtu.be/vMwTzURWXmk

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

From what you are describing it sounds like the engine is misfiring under load as you go up a hill. Most common cause of misfire is faulty spark plugs.
You might want to do a basic tune up to restore the performance of the engine.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Here is helpful video of how to determine the faulty spark plug:

https://youtu.be/QTE8k06MzwQ

I have attached diagrams for your reference.

Please let me know of any questions.

Thank you.