Just a thought ...

I still must have the low speed needle very lean to keep mine from stalling while taxing and landing.
Every once and a while during last summer, the engine would exhibit the problem, then I would need to adjust the needle.

It has been noted that the needles change their settings due to vibration.

When I adjust, I move the needle in until it will not transition well ( engine will quit when throttled up), then move the needle out a little until the engine will transition OK.

I am also using a small amount of throttle delay ... this seems to help by allowing a slightly lean setting for idle.

... it's been a good running engine after break-in. Considering purchasing another.

Good luck to all !!!

P.S. I have the spring disconnected.