Rough idle

Hey y'all, so I'll try and explain this as best I can. The car is an 01 325ci. So for about a little over a month ago, my rpm's seemed to bounce when throwing the car in neutral. It'll go down to about 400 rpm then jump about to about 8-900 before coming to idle at around 600. On very rare occasion however the bounce does not stop, it will keep going, gradually falling/jumping a little higher with each bounce. I was able to stop it each time by pressing the gas a little. Then just two weeks ago sitting in traffic at a red light my cars idle became very rough and the check engine light came on. It almost felt like a misfire due to a bad spark plug. I drove it in this funk for about a mile before it came back to life and the cel turned off. I changed the spark plugs that night and it was fine for about a week until the same "misfire" problem came back. I turned the car off for a minute then turned it back on it was fine but it seems to have a very faint vibration when idling at all times now. Nothing major but it's not something I've noticed before. Meanwhile the dreaded bounce is a reoccurring issue every time I throw the car in neutral. Not sure if the idle bounce and "misfire" are related or not. The little research I did led me to the mass airflow sensor, but these engines are relatively new to me still.



Sorry for the wordy post! Just trying to draw it as clear as I can.

Rough idle