I do wear a tight fitting race suit. The first couple times I experienced it, I assumed that I was bumping the throttle cable. I did take care to analyze it, and I’m definitely not.
I should also mention, when the engine does this, the kart in general starts running differently. The engine will bog down in places that it wasn’t a lap ago, and be kind of erratic with the power delivery.
To me, it seams like the kart is running too rich, so maybe I should change the jetting to lean it out. However, why does it run amazing during the opening laps of a stint most days?