318 dodge dart stumbles 5000rpm

you say you rebuilt the carb a few months ago - maybe floats are a little too low or one of the float needle valves is sticking a little??? Too bad your
now a little closer, I have a Edlebrok 750 on my 360 currently but have
a 600 Edle and a 600 Holley sitting around as spares I would have let you
try just to rule out the carb. Personally, I had to stay with the Edelbrock,
the Holley 600 and another 650 one I rebuilt both had a stumble right off of
idle that I couldn't resolve in either Holley carb, the Edelbrock don't do it.