I've been having a suspected vacuum leak on my 68 Charger, 383 with edelbrock DP4B intake. I sprayed starting fluid around the edges and the rpms jumped so I got a new Felpro valley pan gasket and got the fiber gaskets also and installed. Seemed to run a little better but not much so I tried the starting fluid again. The rpms only jump when I spray by the heat riser ports on the head. Does this mean my intake may have a crack?

likely the intake is warped & since it has to come off again anyhow I'd have it checked/slightly milled to true it. Felpro has the thick paper gaskets & superformance on here has thin ones. Use whichever you need to get bolt hole/port alignment height the same between the head and the intake in the "V" slope

Last year when I was fiddling with trying to stop my detonation issue, I ran across several other small issues that may or may not have been problems. One was the intake gaskets. Some here mentioned that a poor sealing intake gasket could allow oil to be drawn up from the valley by intake vacuum and sucked into the chambers. In my case that turned out to actually be true. I tried using my Edelbrock RPM intake directly against the steel valley tin/pan which was directly against the edelbrock aluminum heads. I did have gaskacinch at every joint but there was still oil seepage. I switched to adding paper gaskets on both sides of the valley tin and my oil seepage problem went away.
Not sure how much of a vacuum leak I may have had though. My idle vacuum has always been sorta low by street car standards.

but it seams to only happen when I spray right on the cross-over hole.

Check for flatness of intake after removed, have it milled a little to flatten up if needed. Then check flatness on head at the cross over and also look for cracked cross over around the outside of it.

MLR426