P0304, VSC, ABS, (!), brake. 12v battery? Something else?

2009 Prius
246k miles
Bought 4.5 years ago, no major events until now. Changed oil routinely, replaced a few minor things, but haven't done much to it lately.
Working on selling so replaced spark plugs 12/28/19, had CEL for catalytic converter and replaced that on 1/1/20.

Yesterday while driving had some slight stuttering, hard to be certain at the time but felt like a misfire. Happened at relatively low speed and under load (acceleration). ICE was running due to heater on, but kinda felt like maybe ICE was turned off briefly then back on a couple times. Got onto highway and no problems.

Got off highway, while accelerating and it's clearly some sort of misfire, even had a CEL briefly that also flashed for a bit then went away. Was able to stop shortly after and check code, P0304, confirmed misfire theory. Plugs just done so maybe a coil pack? Grabbed a coil, but there was no way to replace where I was and it was a 15 mile drive home, so I called AAA to get a tow and not do any (more) damage (sulfur smell indicated I was probably damaging catalytic converter).

When they dropped off the car I got in to adjust the parking and the dash lights lit up like a Christmas tree - VSC, ABS, (!), brake. They weren't on before getting towed. Doing some research on here that could be 12v, but I haven't done any testing yet. But I've also not seen any of those threads also indicating a misfire too.

Are these possibly all related? I already called the tow company and have to call back during normal office hours regarding the dash lights, but I'd hate to get everyone riled up for a simple fix.

 

Update while waiting for mod approval:

12v battery test
No load: ~12.5V
Load: >11.5V (I think lowest was 11.8, but don't recall)
Hybrid system on: 14.3V

 

2nd update while waiting for mod approval:

Remembered that my OBD2 scanner is capable of checking ABS codes.....

Code C0200
Code C0205

Google says that's both left and right front wheel speed sensor signal malfunction.

So it sounds like my two problems are not related. Gotta call AAA to update them, as they are handling things with the tow company for now. Not sure if it just needs a reset or if it needs repairs. Hopefully have answers soon.

 

Another update

AAA wanted me to charge the 12V, so I put a 3A charger on there. My charger even lets me specify it's an AGM battery.

AAA also wanted me to drive the car to see if the wheel speed sensors would reset themselves. I don't like it.

Getting a mini VCI cable, reportedly 2.0.4 firmware, and will check for any additional codes this weekend. Doing that before any possible driving, even at low speeds. I still don't like AAA's suggestion, and I'm getting cranky that I'm having to do all this diagnostic work rather than them just offering to pick up the tab. Hell, even justifying it as driver safety would be nice. I thought that was something they cared about.

Planning to also swap coils between cylinder 2 and cylinder 4 and find out if the code follows the coil or the cylinder (chose cylinder 2 because it's not the same position on the opposite side of the engine, and it's easier to access without taking off the relay box in the event the code follows the coil).

 

Might have figured out the misfire. Looks like I had some water intrusion under the coil grommet. Will monitor that and see what happens. Getting TechStream software today and will check for any other diagnostic data before clearing the ABS codes and see where we go from there.

 

I'm guessing that things are ok. Got TechStream connected and checked for additional codes, there were none. Freeze frame data (below) indicates the back wheels were at 18 MPH while the fronts were at zero, indicating the errors probably got set during the tow service.

Haven't driven it yet, but fingers are crossed. Gonna start low speed doing a circle around the neighborhood.

 

Autolite Iridium. They had a rebate going about 1-1.5 years ago and it took me forever to finally get around to doing the work.