How old are your spark plugs?

Ok, not too bad. It’s possible that new plugs will smooth it out, it’s hard to say from here, lol. I know I have had bouts of rough idle on cold start before, and it was usually spark plug or coil related, but they aren’t the only culprit for that by any means. If you do any of your own maintenance, you could take a couple of minutes to pull them out and look at them, to see if it’s lean or if they are oily or sooty. With no codes, it can be kind of hit or miss with things like this. But take anything I say with a grain of salt, I’m not an expert, just a guy who tinkers with his own Mini to save $$. It seems like these things just have moments of rough idle when cold sometimes, and if it isn’t plugs or a fuel pump or something you can point to, they just sort of do it occasionally. It could be just a bit of bad gas...... who knows sometimes

The way I monitor most things except boost, is with dash command on my iPhone with an OBD2 dongle, (I mounted a boost gauge) you can see fuel rail pressure with it. Not sure what it’s supposed to be, but it does vary depending on what the car is doing. I think mine is usually somewhere between 1500 and 1800 psi but I don’t know for sure, I’m just pulling that number out of my a$$ right now, since I haven’t looked at it for a while.