stock 1973 318 V8 starts but won't idle without foot on pedal

A vacuum leak is my #1 possibility. I tried spraying quick start all around the edge of the intake manifold and the carburetor base but did not get a real reaction anywhere. I am also inexperienced at this test and I don't really know what is supposed to happen if there is a vacuum leak. Maybe a positive reaction is more subtle than I was looking for.