Any mechanics that can help diagnose this?

I have a 2011 Prius. A month or so ago I got a P0301 code and replaced the spark plugs and ignition modules. It ran fine until today when it started misfiring again and again I have a P0301 code. I’ve also noticed that while in Park with the gas to the floor the RPMs rise and fall while my foot stays hard down. I also noticed an ethylene smell in the cabin when it started misfiring. Also, starting from a stop it misfires a bit, but once up to speed it’s fine. Before I start going to the next thing I can think of, which is to clean the intake manifold and EGR valve, do you think that would even be the issue? If not, then what?

Edit: it only misfires for a few seconds before going quiet again, even just sitting in park