What does it do exactly?
Is it like firing irregularely or is it backfiring or does it bang in the exhaust?
Could be due to an induction bias. Both mine suffer it, the plunger runs richer on the left pot and the SA on the right.
This can be heard at idle when there's like two or three combustion cycles that just seem to puff, and then a sharper combustion, after which again there's a couple of puffs.
Doesn't bother me too much at the moment but one day I'll dig in to that en get it solved...
... one day.