EGR Vacuum Line?

I just changed my EGR and EGR sensor. Call me stupid or whatever but I noticed a place to put a vacuum line on the EGR. I'm thinking this is why my car runs as poorly as it does. What does the vacuum line do for the EGR? If thats what goes there. Next question. I'm really not sure if since I've had the car, there hasn't been a line going to it. I did some searching around my engine and I've found 2 vac. lines that are cut in the corner closest to the passenger side. Which vac. line goes to the EGR? And what size would it be? Thanks much!
 
See http://www.veryuseful.com/mustang/tech/engine/images/88Stang5.0Vacuum.gif

Or

http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

The EGR gets a white line connected to it. The 4 hose coupler has one blank position with no connection.

The back side of the 4 hose coupler has red tube the couples to the white tube that goes to the EGR. The red tube comes from the output side of EGR vacuum regulator

The green tube goes to the coupler and then connects to the intake manifold. This line has been changed on mine, and I do not know what the orginal color was for the line that connects to the intake manifold. The green tube connects to the input of the the EGR vacuum regulator.
 
To add a bit to jrichker above, intake manifold vacuum does not go directly to the egr valve. Manifold vacuum goes to the egr vacuum regulator/switch (located on the firewall). The output of that switch gets connected to the egr valve. The computer tells the switch when/how much vacuum to deliver to the valve. Vacuum when delivered by the switch overcomes a spring/diaphragm in the egr valve causing it to open and admit regulated amounts of exhaust to the intake.
 
Super Lost

After reading these post I went out to my car to look for the mention vac lines. The only colored vac lines I have are a green one going from my intake to fuel reg and a white one that is cut. The white line is on the back side of the strut housing (I guess you can call it) facing the passenger firewall. All other lines are black. The smog pump was taken off along with the A/C. I don't know what lines go where and what lines should be plugged. Sorry to keep nagging about this. I just want my car working like its supposed to be. An actual pic of what I'm supposed to be looking for would help out a good bit. Thanks!
 
The white line in the center goes to the thermactor diverter valve. Not needed in this case. There are two long black lines. One goes to the rear of the intake to one of the small vaccum ports, and the other goes the smog pump. Cross those out. There should be one shorter white line left and that goes to the EGR. Follow jrichker's post on how the coupler plugs together and you'll have it. If this is still a bit confusing, I'd suggest going to a junkyard and seing if they have a 5.0 that hasn't been mangled in the front. Lift the hood and see what it looks like. The yard I use let me have the coupling for free (my lines were all broken) and I found out how to run it to boot. Just carry a sheet of paper to write down what you see.