Looking at the few mustang forums I get on, seems there's been quite a few issues with that specific area lately. The tube that the hose is connected to is more than likely cracked. It's molded to the intake manifold and the intake manifold needs to be replaced. I read one post where the guy cut the tube off evenly, tapped the plastic, and installed a barbed fitting to connect the hose to, but a proper fix is to replace it.
I have a pi intake I'm looking to sell if you're interested.