Engine Knocking - P0403 and Misfire

Hey yall, Im new here as of right now.

Mileage: 236K
Owned since: OCT 2017
I've driven across the country, multiple day trips since 2017 well worth 50-100 miles a day.
Excellent condition aside from the recent KNOCKING. it is very short lived. Some startups sound better after cleaning the egr valve and manifold, also cleaned the cooler, not the best cleaning however due to time.

I ordered NEW egr valve and egr cooler, will replace this week should weather permit.

Replaced manifold, coils, and plugs in 2021. Since then, I've had to make trips to Pennsylvania and Tennessee, also Georgia and South Carolina. I live in Charlotte, NC. Ive rarely had engine lights since I have owned it, in fact, I have heard mechanics say it is in great condition given how much driving I have put on it for 5 years, about 100K miles or even more.

I will order new fuel injectors and do the head gasket. I am aiming to get 300-500k miles out of this car. Any help on my recent mishap would be appreciated.

 

@Mendel Leisk Hi Mendel, Ive read about you in 2021 when I had an intake manifold issue. Lately, I have had another issue. I have been reading your wisdom and knowledge here. I wonder if you could take a look at my post. Thank you!