Carb spacers and Edelbrock 1405's

On a moderately built 305 with a Performer EPS intake manifold . This thing runs like a scalded cat , did everything I wanted - except idle . No matter what I did it would idle for a few seconds then just stumble and die . Turns out that the spacer under the carb was the problem . I had to use a spacer in order to have a vacuum port for the brake booster since this carb doesn't have a port on the back . Turns out that because the spacer is open without a center rib (and the manifold has one) it causes problems with the idle circuits . The solution turned out to be getting a spacer that has 4 holes instead of the open one . The new spacer didn't have a vacuum port ... but it had enough meat to drill and tap for one . And now the truck idles in gear without dying . I haven't driven it yet to see if it runs differently on the road , but I don't expect any significant change in performance .