Vacuum system freeze up???

[MotorCityMadman]

We had a cold snap around here lately. It was down to -36c at night and about -25 during the day. It's now -15c. Now the fuel shutoff doesn't work and the brake boost works for a few applications and then is gone. The fuel shutoff problem in the cold happened last year in the cold as well but not the brake problem.

Is this indicative of moisture in the system? Or is this a vacuum problem, ie. a poor pump or leak? What are your experiences those of you in cold environments?