2006 Elantra Running Rough

[haveydog1994]

Hello everyone,
I have a 2006 Elantra, GLS, 2.0 liter, 5 speed manual.

I just bought this car and it developed a rough running issue after driving it 200 miles. At idle and under load at lower RPM the engine "stutters". The car does have the CEL on and here are the codes it has been throwing. P0447, P2251, p2297, and P0302.
I know that the O2 senors have issues but I didn't think that the O2 sensors would cause a rough idle? The last code says that there is a misfire detected on cylinder 2.

I have changed spark plugs and plug 2 was noticeably burned down (plug to electrode) relative to the other plugs.

I have also cleaned the MAF sensor with CRC MAF sensor cleaner.
I replaced air filter.

I was wondering what you all would suggest as the most likely option to cure the rough running/misfiring.

Thanks for the help!!
Josiah