I think I need to go to Carter BBD Skool !

Bugman said

Intake manifold too cold ,thus less than ideal fuel vaporization,can you lengthen the time the choke stays on?

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I installed an intake hot water heating plate where the stock exhaust header attached.

I got ticked and rotated the choke so far closed that at operating temp the choke flap was still partially closed. It didn't stumble at low and mid-engine temps then.