Might be cracked coils. They'll cut up when everything warms up.
Not sure that this is related directly, but I wonder if it's way too rich. Might check all mixture screw settings. Turn each one all the way in, very gently, counting the number of turns exactly, to the 1/8 of a turn. I think we mostly agree that they should be about 2-3 turns out from the lightly seated position (bottomed).
May not help, but won't hurt to check.
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