There are few reasons you could have the misfire. Bad catalytic converter is one of the reasons that it can misfire. Then again it could be due to other factors.
I have attached the complete diagnostics for bot code P0431 and P0303.
Go through that step by step process, it will help you narrow down exactly the issue that you might have.
As for overheating, does it go all the way to red or runs hotter than usual?
Let me know of any questions.
Images (Click to enlarge)
Friday, September 10th, 2021 AT 10:17 AM