Cylinder 4 misfire and several other codes

Hey all, I'm not super mechanically inclined and would like some advice. I bought my 2009 back in March with 160k, it had a generic evap code that I ignored. I had my mechanic change the spark plugs and all the fluids right after I got it.. Fast forward, drove it all over the country absolutely flawlessly, used it for deliveries and road trips ect....
During this time the cat was stolen and replaced with a cheap Amazon one, which I know is throwing one of these codes and I'm not worried about that one unless it could actually be an issue.

It now has 198k.
Today I decided to read the code again and turns out now that's 4 different codes popping up.
Po 304
Po455
Po441
Po420
One of them is for a misfire in cylinder 4. Which I had in my previous prius which was cleared up by changing the spark plugs. I did a little reading and it seams like I should change the spark plugs again and change the #4 coil pack. Besides that, anyone have any suggestions?? Car is running just slightly rough and the fuel economy has dipped 2-4 mpg in the last week or two. Everything else seams great.

When shopping for coil packs, is there a specific brand I should go with? I'd like to order off Amazon, looks like they run a pack of 4 for around $40-60 bucks, any input is appreciated.

Thanks so much in advance, thankfully I have a buddy nearby with a well stocked garage and who is very mechanically inclined so he will help me with basic stuff. Just looking for advice from you guys here that are specifically familiar with these cars.

 

I'm burning maybe half a quart every 1500-2k miles, so nothing abnormal right? Should I stick with having O'Reillys order a set of coils instead of Amazon? I know denzo makes a lot of the oem parts but didn't see any coils made by them.

 

I have not started digging into the car yet, I will pick up one coil and a set of plugs and take it to a buddy's garage tonight. I'm not sure of the quality of the plugs but regardless, I'm hoping just replacing them will clear it up. How long do you think ngk plugs should last?

 

Yeah it seams to be running a noticeably rough, specifically seams to start rough like give a bit of a shake when kicking on. The other thing I noticed, when I'm sitting in ready mode, when the ice kicks on to charge the battery, it turns on but doesn't idle high enough to charge the battery for a few seconds, it just kinda hums and lurches slightly before the rpms get higher then it smooths out.

 

Ok, I got a new ignition coil and a set of denzo plugs and will install them tonight, fingers crossed that clears up the misfire.

 

Ok, all new plugs and replaced #4 coil. Lots more power. One thing that its still doing is when I'm idling and the ice kicks on to charge the battery, there tends to be a pretty significant lurch as it kicks on. It's very smooth while driving, but that first kick on to charge the battery just doesn't feel right. Maybe this is normal?? I'll get the codes checked again tomorrow to see if misfire code is gone.

 

Not to bad, but the one on #4 looked a bit worse. Definitely dirty, but not super bad.

 

Throttle body will be super easy, ill have to looks up where the maf sensor is.

 

Quite possibly. Although if there was a significant issue with rings, wouldn't I be burning quite a bit of oil? I'm going to get some basic tools and start doing more of this kind of basic stuff myself, the throttle body looks like it was be very easy, the rings would be quite a bit more difficult, atleast based on a teardown I watched.