on two cylinders. But I wasn't sure how you were determining that it was only one or which one. Pulling coil pack connectors should work but at idle it can be difficult to tell which is bad for sure. Why not run the Nissan Data Scan power balance test and compare the wiring color codes as a sanity check. I would think CAS is unlikely but PTU still could be an issue since a weak spark could still look pretty bright. Could you swap the ptu from your car as a test? Did the plug look wet when you pulled it? If you start the car with the plug out do you see fuel vapor come out of the plug hole? ( this is tricky since if the air is humid compressing it can cause vapor to condense so you need to be sure it is fuel that you see.
This is a real toughie, you need to be methodical and practical to be sure you eliminate each system completely.
