Thanks for the link, Haasman. I don't think that fellow's problem is much like mine, but he certainly has put a lot of diagnosis into it.
My problem used to be worse, and included a stall when I would come to the first 'stop' of the morning. This was due to a ruptured hose from the idle valve to intake manifold, and is why that item is 'new'. There is still some old rubber in the system, and the feel of it at connection points is a bit loose - potentially air leakage that might be significant at low flow rates.
The bottom of the air meter unit is rubber, molded to slip over the throttle body. A port on it attaches to a hose that goes to the input of the idle air valve. Neither of these parts has been replaced, so the plastic joint connecting them fits suspiciously. The only 'unknown' section is the area I mentioned between the manifold port and the cam cover port. It LOOKS like unrestricted joins of straight rubber tubing, but that wouldn't make sense. I may end up disassembling it - risking ruptures developing - since it would appear any rubber with the right ID will work.
Still, the nature of the problem is that it disappears if I turn the ignition off then restart. Idle returns to 700 rpm. This would appear to hint at Stevebfl's finding of resistance in the OVP relay, but I can't get the @#$ thing to come apart. So, I'll splice in a diagnostic connection to monitor it's voltage output while I drive, and see if that is the problem. If it's bad, it's cheap to replace. If it's good - real expensive!