Just an update since my last post on subject last July.

In the past couple of months, had used the vehicle more day-to-day in heavy city traffic. Eventually, the erratic low idling under load again manifested together with random non-starting a couple of times (reference to my related post on erratic starting).

Since then, had replaced spark plugs, battery, valley/ intake manifold gaskets (discounting unmetered air) & one injector (was apparently running mostly on just 7 good cylinders).

Seems to be running better now (engine starts readily on the first turn of the key & runs/ idles more smoothly).

Still keeping the IACV I recently bought (Standard/ Intermotor) in reserve, in case things suggest it needs replacing too.