[clay68c10]

I’d set the idle to around 650 in drive and see what happens. What’s it idling at in gear now?

You may have to play with initial timing and idle screw adjustments (throttle plate and mixture) to get it so the neutral to drive rpm difference isn’t too extreme. Like add timing and lessen the throttle opening, or change up ported vs manifold vac to the can. The usual hide the salami carburetor adjustment game...