Engine stutter at 1500RPM only?

Just yesterday, car sits for a few weeks at a time usually.
edelbrock 1406 carb, only does it at part throttle from an idle, then the rpms jump up after the stutter and all is fine, even at WOT. Unresponsive only around 1500rpm. Even when driving the car will jump forward after that rpm.

idle it for a minute (on a level surface) then pull the rods/top & the fuel needs to b at the notches in the float baffles on each side. I think the dry float setting is 7/16". Need a .098" or richer pri jet(s) in there and I'm assuming this stumble is when warmed up/part throttle & if happening during warm up in addition the elec choke can come off way too fast causing a lean stumble and hurting your gas mileage if that is imp. If richening it helps the part throttle bog then concentrate on dialing in the "cruise" step & might note what springs are in there and can run a vac gauge out & taped to the windshield to find when the bog is. Get a baseline on all the details

Started by cleaning out the carb, and shot a video of how when I hold the rpms exactly at 1500, the rpms jump up a few, then back down to 1500, then up a few again.