If it ONLY happens under hard acceleration, that sounds like a BPC (boost pressure control) valve that needs cleaning (blowing out with compressed air). The clue is it happens only when already at normal speed, AND pedal down.
When it gets full of crud and starts to stick, it can cause a momentary overboost/fuel cut condition. It feels like that car stalls for a fraction of a second, then accelerates, then stalls again, sometimes two or three times.
A mechanic cleaned it with shop air, but suggested I should just use a can of compressed air once a year or if it happens again. Or just buy a new valve, which should last for a few years before it gets gummed up. He did not seem too keen on a new part in this case though. Said on older engines, people sometimes pay for the new part, and are still back a few months later.
