Hoping someone can help currently have a focus st3 on the odd occasion while driving it has a hesitation for couple of seconds has a flat spot but if u keep your foot down it clears and pulls fine. Also when it does this the boost gauge drops and once it’s had its moment gauge comes back to normal when I first got the car it done it but recently getting more frequent. It’s almost like a misfire like it drops a cylinder. It’s had new plugs someone scanned it and came up with mass air flow sensor which was changed but still doing it. I’m hoping someone can point me in the direction of what it can be as at the moment spending money on it I haven’t got.. many thanks in advance..