Persistant P0300, P0301, P0302 engine misfires on idle.

I'm getting intermittent misfires when the car idles, the exhaust has a subtle putputput sound and puts out the smell of gas when it misfires. Initially, I had misfires on all 4 cylinders but I replaced all the spark plugs and ignition coils and now it's just cylinder 1 and 2.

What tried first:
New spark plugs (4x DENSO Iridium Power 5303 Spark Plug) (I did not check the gaps but they all looked about right)
New Ignition coils (4x Aulink UF316 Ignition Coil Pack)
New MAF (OSKYUO 22204-22010 Mass Air Flow Sensor)

After these changes I still had the misfires, so I then:
Added fuel injector cleaner to the fuel
Tried cleaning the throttle body (I used a toothbrush while still attached, using CRC throttle body cleaner)
Did an engine flush (Liqui Moly Engine flush) and oil change
filled the tank with fresh fuel (premium)
Resolved the hybrid battery P0A08 and P3000 triangle by replacing bad cells and rebalancing pack.

Still misfires... I'm a bit at a loss here. Any ideas? I won't be able to register the car unless I get it resolved.

Car has 370k miles.

 

I switched the spark plugs and ignition coils for cylinder 2 and 3 and I'm still getting misfires on the same cylinders, 1 and 2. Also, I noticed that the spark plug in cylinder 3 is covered in carbon but the one in cylinder 2 was clean. When I got the car, I also remember a fuel lean error code, but it hasn't come back. Any cheap way to fix this? What are the chances I fix it with something cheap like fuel injectors or an additive or ATP Automotive AT-205 Re-Seal? I need it to pass inspection.

 

Good idea, would it be prudent to pick up a fire extinguisher before switching the fuel injectors? The one video I watched on the topic had fuel leaking after he switched them which makes me a bit nervous. I should also mention that there was oil on the spark plug threads. I don't remember the original spark plugs having oil on the threads though, but I did run an engine flush as well as added a very small amount of Liqui Moly MoS2 and small amount of AT-205, so I don't know if the engine flush or something else caused oil to temporarily get get through the gasket.

Also, if it is something like the head gasket, what's the cheapest way to get help on that? It seems significantly above my current ability and tools, unless there is an easier way to get the head off than the video I watched.

Would a gas test on the radiator work for testing a head gasket failure? Seems like it would be a lot easier than doing a compression test.

Any thoughts on Steel Seal or are there any other non-teardown options that won't cause problems with the heater core or coolant system on a Gen 2 Prius?

 

My original idea was to use the cheapest parts to help troubleshoot by eliminating the common/easy problems, and I can switch back to the originals or upgrade for longevity later. No plans to sell the car as I need it (as long as I can get it registered), and I'd never sell a car without disclosing all the known issues. The AT-205 was because I thought it might help if there was a worn piston ring and also there may have been an oil leak (although it could have just been because the dipstick tube wasn't seated due to a missing bolt). I added the anti-friction mostly out of curiosity and to see if it would help in case of engine wear, but only about 10% of the recommended dose because the oil level is already at the max fill line. The engine had been run for at least 15 minutes almost totally dry (it was almost seizing), so I assume there is a lot of engine wear and also possible warping. However, the engine seems to run surprisingly well now except for the slight misfire on idle.

The previous owner did mention that a mechanic had said something about the fuel system before (I think they mentioned fuel pump), but I have no idea what they did to diagnose the issue and since I replaced the sparks it's not misfiring on all 4 cylinders (only the first two). I didn't notice oil on the throttle body when it was cleaned (I did this before the engine flush). I haven't noticed a coolant leak and the levels seem fine, although the coolant in the engine overflow tank is clear, so it's not Toyota coolant. I don't know if the Prius has an engine overheating light, but it had no codes relating to overheating except for the inverter which I fixed by replacing the pump.

I have the veepeak bluetooth reader, not sure which is the best app to use with it. I'm just using a free app at the moment which I can't remember the name of.

Also, I may have overfilled the oil the first time due to the dipstick not actually being seated.