Are you seeing any CEL codes? Typically with any VAC leak you'll get a CEL especially if it's bad enough to cause the engine to idle erratically.
Is it just a bad idle (erratic) or are you sure it's a true miss of the engine?
Did you post up video?
2009 Challenger R/T - Arrington Forged 6.0L and Magnacharger Supercharger - 553RWHP 627RWTQ