Help Identify This Vacuum(?) Line.

This should help you very much, as it helped me out alot with my car. When I bought my '89 LX, the the vacuum lines were A MESS. The EGR was hooked up to the PCV and a few lines were left uncapped. Vacuum leaks galore! It didn't help that my lower manifold gasket seemed to be sucking in air as well. I went over and replaced ALL of my vacuum lines and did my upper and lower intake gaskets. My vacuum lines were looking to be in bad shape as some were cracked/splitting and I personally didn't trust them. You don't need to do this.
I do NOT know if this is fact or not, but I believe that speed density cars have a vacuum line going to their MAP (Manifold absolute pressure) sensor. Between these two diagrams, everything else should be the same. My '89 does NOT have a vacuum line going to this sensor, as it has a MAF sensor along with having a MAP sensor.

From the UPPER MANIFOLD, there should be...
-A large vacuum line going to the vacuum tree.
-A vacuum line going to FPR (Fuel pressure regulator).
-A vacuum line going to your MAP sensor (since your car is an '87 it should be a speed density car from factory. Only '89 and on have MAF sensors, for the exception of '88 California cars)
-A large vacuum line going to your PCV. The PCV is located on your lower intake manifold, it's a little plastic piece with a ball on the inside that slides into a rubber grommet. Below the rubber grommet, there's a metal mesh filter that slides into the intake as well. I bet yours is real gross, I'd remove the filter using a small screw to thread into it a bit and pull it out. I cleaned mine with Simple Green. Use whatever you feel like using. I believe a replacement is under $10 if you wish to simply replace it.
-A vacuum line going to your purge solenoid, which then goes to your vapor canister, which then goes all the way back to your fuel tank. If you have trouble finding the purge solenoid, the wire connector going to it from the fuel injector harness is right by the oil filler neck. Or just follow the vacuum line from the vapor canister.

For the rest of the lines, reference the diagrams. Good luck and report back!

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Also, in reference to post #5, I'll identify what's what between the three switches/solenoids to help you simplify things.
The top thing is the EGR vacuum regulator. The top line (I believe it is gray from factory) goes to the EGR. The bottom line leads back to the upper intake manifold, but before doing so it'll meet a vacuum T. Reference your car to verify this. (Assuming that this line has not be tinkered with)
The two bottom things are your thermactor air diverter solenoid (TAD) and your thermactor air bypass solenoid (TAB). I don't know which one is which in terms of what one is on the left and what one is on the right, but you should be able to easily figure this out. I hope this helps!