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?