Just out of curiousity, is the distributor "tight" in it's mount? Is there any slop in the distributor when you twist and shake it?

I recently learned that the fly weights on the bottom of the distributor can become dislodged and screw up a properly timed engine.

The fact that it's hick-upping under load points improper advance (vacuum as MT pointed out) but it could be under the plate with the fly weights??

I dunno. Justa thought

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