Morning,
Don't think the filter is to blame. Probably need to synch the throttles. They get a little "jumpy" when they're off. Get them tuned properly so all four throttles are flowing about the same, and she should quiet right down.
Or, buy a mercury stick, and tune them yourself. A lot of us have, and use them. They work great. "Butter" smooth.
Common symptom when they fall out of balance, and they will. Normal maintenance.
A.
