Sure sounds like the monovalve to me. It's a relatively rare failure (unlike the older styles). I think I'd try replacing that first. BTW, your vent temps are pretty high... I'd expect <40°F while cruising at speeds above 40mph. My vent temps only approach 60°F when poking along in stop-and-go traffic on a hot day.

I'd still check all the vac pods while you're at it, this is relatively easy after you access the 7-port manifold behind the glovebox. Each line should hold vacuum... if not, the pod on the other end is dead.