That might be the flow valve that mounts on the passenger side of the intake manifold. When that EVAP stuff gets old and dries out, it's almost worth replacing all the little stuff that could leak. I did the cannister, rear purge valve, some hoses, the stuff up on the intake. My cannister had dried out and the charcoal was getting sucked all the way up the line and into the intake! The cannister and dried out lines at the back of the car can be a real PITA to deal with so be prepared!
Go to this site for some good information
4th Gen Tech Articles
Here's a shot showing a lot of the EVAP stuff up around the engine.
And the rear stuff.
