Thanks Max.

Here's what happened when I started checking. First place I tried was the
fuel pump regulator vacuum hose. Got the guage on, started car, lo and
behold--zero pressure. WT heck? Shut off car, replugged FPR, plugged guage
into distributor hose: 13 in., slight wavering, looked good. It turned out
the FPR vacuum hose at the manifold was completely severed by the hose clamp
I had on there, but couldn't be seen because of its position way inside
there and because of the hose clamp itself.

No wonder there was surging idle sometimes!

A new check showed vacuum at 15-19, depending on where I had the throttle
bypass screw. Steady, not fluctuating.

I reset the idle speed with AIC bypassed, reconnected, runs like a champ.

I don't have any of those vacuum restrictors the Bentley shows. Are they
necessary?