2015 BMW X5 xDrive50i Issues With JB4 Tune

[ClassyF15]

Hello everyone, hope all is going well.

I've been eyeballing this forum for quite awhile and it seems like this community is pretty supportive, so I'm hoping to get some help with this car.

A little background - I bought my 2015 BMW X5 xDrive50i (N63TU) around 4 months ago. So far, I've been loving every second of it. Zero issues...until today.

Around 1000-1500 miles ago, I changed my spark plugs. I ended up going with the OEM Bosch plugs, using the OEM gap specs. 5 days ago, I got my BMS JB4 piggyback tune in, and got it installed. Up until today (about 600 miles later after our roadtrip) I've had no issues and have absolutely loved the tune. I kept it on Map 1, which is 5 PSI over stock as I did not want to compromise its reliability. This morning, I was running some errands and gave about half-throttle to around 60-65 MPH while merging onto the highway. The car started shuddering, followed by a check engine light and the drivetrain malfunction message. I got to where I needed to go, and parked the car. About 25 minutes later, I started the car and started driving. No codes, no messages, no shuddering. However, at speeds of 70-80 MPH, I noticed an intermittent hesistation, clear indication of a misfire.

I did some research. I hear left and right that these cars, while tuned, need to run the NGK 97506 plugs gapped at 0.022. So, that's what I spent my evening doing. Finally, after installing these new plugs, I started the car. I felt like I was in a drying machine. Insanely rough idle, flashing CEL, and of course, the drivetrain malfunction message. I don't have a good code reader, just one that'll get your basic codes. I plugged it in, only to see P0301 (Cylinder 1 Misfire). Then I started the car and checked again, code is gone. Then a minute later, code is back. The coil is good and sat properly, and the coil wire is good and connected as well. The spark plug doesn't look bad as it is a brand new plug, but I'm not too familiar with the mechanical aspects of engines so maybe I'm missing something...

All in all, I'm stuck with a car that is now running substantially worse than it had before. I'm 99% certain that the issue is spark plug related given that I had zero issues prior, intermittent issues with the last set of plugs, and an plethora of issues with these current NGK's. So, where could I have gone wrong. Is the tune I got to blame? Should I have stuck with the OEM plugs and changed the gap of those? Should I have left the gap of the NGK plugs alone? I hate that I had zero issues and now I can't even drive it!

Any and all help & advice is greatly appreciated.

[Fknid]

How do you know the coil is good? If you move the coil to another cylinder does the mis-fire follow? E.g. Swap coil from 1 to 5.