Best to post questions here on the forum for everyone. I tried replying to your PM twice, but the website lost my answers, so unreliable. Anyway, many people here can answer your questions, and faster.
The part in question is the Vacuum Control Valve (VCV). It is supposed to leak. It sends a partial vac signal to the modulator on the side of the transmission to control shifts, to simulate intake vacuum of a gasoline engine. It is like a "voltage divider" with the resistance of an upstream orifice in the tube to the source. Best to add a small filter on the black tube which sucks "clean" air from the cabin, thru the firewall grommet.