Please let me know if I’ve put this in the wrong place, I just got a 2017 Focus ST and it’s had a shudder for a bit now. Only during idle, the rpms never actually move so I don’t think it could be a vacuum leak. No codes, doesn’t effect the drive ability of the car at all. I thought it was because the dealership put 87 in it but it does it even when it’s got 93. Is this normal? I can’t seem to find anything anywhere about this, and when I called the dealer the service human basically said come back when it’s warmer if it’s still doing it. Im near DC, it’s not THAT cold.