Ford Repair: Vaccume problem, ford crown vic, vacuum diagram

Question
I have a 1990 Ford Crown vic with the 5.0 in it.  It has the AOD transmission.

Currently the wire that goes to the (relay/whatever) which is part of the EGR valve is unplugged.  with this unplugged while stepping on the gas the car looses vaccume and the vents inside the car seem to close.  nothing comes out anywhere.

When we plug that wire back in the vaccume is no longer lost and the vents function correctly.  However,  The vechicle then builds up pressure in the fuel tank.  The fumes from this are horrible.  Upon removing the fuel cap from the tank a steady breeze for lack of a better way to describe this comes out of the fill tube.  

I imagine that there are vaccume lines crossed somewhere that is causing this but would like a second opinion.

Thank you

Answer
Hello and thanks for the question...I'll try to help.
On the front radiator support there should be an emissions decal which has the vacuum diagram for that engine. Trace and follow the diagram.
The EGR and your fuel tank building pressure aren't in the same system and shouldn't be creating a problem.
Erik