1979 3.3 litre emission control problems

[84LX89GT]

Although it's not a whole lot of help have you checked out the vacuum diagram that's posted in the engine bay/underside of hood. The diagram shows where all the lines go, although you have to figure out what components the abbreviations stand for.

You could also get a chilton or haynes manual and check out their vacuum section.

A chilton's book i have also explains how the ported vacuum switch works based on engine coolant, which controls EGR operation and at what temp it allows the EGR valve to get vacuum.
According to the haynes manual i have, there is a vacuum line from the "EGR" vacuum port on the carburetor that goes to the middle line on the EGR ported vacuum switch, a vacuum line with a one-way check valve from the spark advance PVS goes to the top line on the EGR PVS. and the bottom line goes to the EGR valve from the EGR PVS.
There is also a spark advance vacuum system with a PVS (cooling PVS). The spark port on the carburetor goes to the top vacuum line on the cooling PVS. The bottom line from the Cooling PVS goes to a manifold vacuum fitting probably tapped into the intake manifold (or in your case "intake log") and the middle line from the PVS goes to a vacuum delay valve, then to a "T". One line from the T goes to the check valve and into the EGR PVS system, and the other vacuum line of the T goes to the vacuum advance on the distributor.
This was a general schematic they gave so hopefully you can figure out something or get a picture (a picture is wortha thousand words, right).
So anyway, i hope this helped somewhat,
good luck