Vacuum Leak, Rough Idle?

[__PhaseShiftDown]

My car started to idle rough yesterday, a bit lumpy and shakes a little bit. Saw on the EBC my vac reading is a bit low, so I figured there's a vacuum leak somewhere. I sprayed some carby cleaner around the engine and the leak seems to be coming from back of the engine somewhere near the firewall on the driver side (revs picks up). Its not the vac line that goes to the stock boost gauge sender. Is there any other vacuum line around the back some where? What else could it be?

[XKLABA]

Sorry on what car?

[gt-ahhh!]

"Saw on the EBC my vac reading is a bit low, so I figured there's a vacuum leak somewhere."

what is low? where should it supposed to be at idle? my greddy profec b ii sits around -70 (7 psi) at idle.

[__PhaseShiftDown]

"Saw on the EBC my vac reading is a bit low, so I figured there's a vacuum leak somewhere."

what is low? where should it supposed to be at idle? my greddy profec b ii sits around -70 (7 psi) at idle.

Oops. Car is a 32GTR.

The EBC is a HKS evc3 and the reading that I usually get is 480mmhg (9.2psi), but now it is sitting at around 420mmhg (8.1psi) if that helps. The car idles at around 1100, which is pretty much what I get usually, but it vibrates a bit and it seems to be using more fuel as well. When I floor it, it feels tiny little bit sluggish, but overall drives fine when boost comes on.