Hi, im troubleshooting the vacuum system in my 1984 DT. Here is what ive found so far.

1, the vacuum is fine when taken at the brake hose.
2, The vacuum is fine when taken anywhere else.
3, the only time the vacuum disappear is when (any) throttle is applied.
4, I plugged the hose going to the lower of the 3/2 valves(on the valve cover) and then the vacuum decreased proportionally with throttle application. I took the car for a drive in this configuration and the shifts seemed to be smoother (although 1-2 shifts were still hard)
5, there is no vacuum going from the white line originating at the 3/2 valve to the vacuum control valve.

What does the lower 3/2 valve do?