Immediatley behind the battery (just behind the flimsy plastic firewall shield) I see what I think may be a vac switch (?) mounted vertically on a metal bracket that's parallel with the dash. There are wires running to it and, what appears to be, a plastic vac line male insert stub projecting from this little black device. Mine has no vac line connected to it. Should it? And if so, what does this thing control and from where does the vac line come? Any help will be greatly appreciated since I'm troubleshooting. I have a '92 2.3.