Intake swap, poss gains?

Not near enough! Add 2 psi.

Jetting up that much is another indication of insufficient fuel delivery. Plus, it slowed down so it may be way too fat if it actually is getting enough fuel.

I'd go back to the factory baseline, maybe +2 jets on each end if you have a spacer, up fuel pressure if you can and see where it falls.

Can't up fuel pressure, using a holley mechanical high flow. Time for an electric?