My BT 20V is idling real low ~400rpm and rough and I'm pretty sure it's due to a loose vacuum hose. For some reason it's just sitting there not connected to anything. Can you guys tell me where it's suppose to go?

This isn't my car but it shows which vacuum line I'm talking about. It's the line coming off the white canister type thing that's located next to the TPS in the photo. On my engine a line comes off from under the fuel rail to the white canister then the line isn't connected to anything. So in relation to the picture my line doesn't loop back under the fuel rail. Where's it supposed to go?
Thanks in advance.