From recent experience:

1) idle had been a bit wobbly for a long time, I'd gotten used to
it.  Replacing the O2 sensor doubled the mixture flip-flop rate and made
the idle rock-steady.  Lazy sensor...Ken Lewis's little meter board would
have shown that.

2) Contact with the ground apparently pushed on a heater hose enough to pop
the coolant-pipe mounting stud out of the ?#1? induction tube.  Result was
nasty hunting idle and sporadic stopping at idle or decelerating to
idle.  Suggestive symptom (of a "false air" leak) was that O2 sensor would
continue to show lean mixture for quite a while -- ten seconds or more
after decelerating to idle, instead of rather quickly going back to
flip-flop once the injectors come on again.  Ken's meter or any other meter
would show that one.

david

--
David Beierl -- dbeierl@attglobal.net