OK, so I find the 2.4 doesn't use the WOT signal and that 3-3-2 isn't such a big deal.

Started it up this AM and it idled a bit high. I KNOW the IAC is working in static test, but just for fun I rapped it with the 18" long 1/2" breaker bar I keep in the cabin. Idle dropped to normal. Huh. Ran for a bit just fine. Turned off, restarted. Hunting idle. Rapped the IAC. Back to normal. Drove beautifully, no stall at stop, even of the "panic" variety.

So it seems the last piece of the "Neglect Me Until I Ruin Your Week Cavalcade" has been addressed. Or will be. Anyone got a used known-good IAC for a '93 240 handy? These are pricey bits, for sure.

Interesting, in retrospect, what a great job the ECU does in compensating for bad/failing components in the system. The IAC's probably been questionable for some time, as I have had it stall on those quick stops before. The O2 sensor going was just the last straw, I suppose.

So I'm calling it fixed. And I know a helluva lot more about the FI system than I did, that's for sure. Thanks to all who took time to reply! I hope this experience was a boon to others...