still chasing my rough idle, misfire. dumb question.

[Meestahbig]

Hi, so I still have vibration at idle. idle rpm is stable and no error codes but after a few months of no issue, yesterday the car was misfiring. I turned it off and back on again, and the misfire went away right away. I wonder if that is a clue.

anyway, I have a smoke detector from Amazon... I have not used it yet. my dumb question is this. if there is no leak in the system, where will the smoke come out of after some time letting it run?

I already changed my valve cover gasket, my disa valve, the rubber elbow. at this point I'm sure it's the ccv or vac lines, or my MAF.

thanks.