On my '98 V6 there is a pcv hose that runs from the passenger side valve cover to the intake manifold. Below this hose on the manifold is a vacuum port that is bare. Is this supposed to have a vacuum line hooked to it? And if not, should it be plugged, or is it just supposed to be left open? Any info would help. -thanx

 

It shouldn't be open. There should either be a hose (going somewhere??!) or a cap on it. I imagine you should have a hose going somewhere though, as they don't put extra random vacuum ports all *****-nilly. What it is and where it goes I couldn't tell you though, best bet is to wait for another 3.9 owner to chime in.

 

You might want to take a gander at the label on the bottom-side of the hood (there should be one there showing a vaccum diagram).
On my '96, the diagram shows 3 spots on the passenger side (1) from PCV valve, (2) to climate contol, vehicle speed control, 4x4 axle [when equipped] and(3) apperantly one capped off.
(Note, the opposite side also has three as well, but only has one going someplace - to the the brake booster)
That's all the help I can give you, hopefully a Gen 2 3.9L owner will step up.

[IMG]local://upfiles/948/90FEEC084FCD476B9B329200CF5D74EE.jpg[/IMG]

 

Ah, pictures prove just what I suspected, 3 vaccum ports on each side, the unused are just capped off!

[IMG]local://upfiles/948/1B9A578C1E5A435DBC7CC3174151622E.jpg[/IMG]

[IMG]local://upfiles/948/4E8AB5551D684F56AAF2B9B3C2B872F9.jpg[/IMG]