Where is the short runner valve on a 2008 dodge avenger?

There isn't a part specifically called a "short runner valve" on a 2008 Dodge Avenger. The Avenger's intake system doesn't use a variable intake manifold with a short runner/long runner valve like some performance engines do. That type of valve is designed to change the intake air path length for better low-end or high-end power depending on engine speed. The Avenger uses a simpler, fixed intake system.