re. Curious High Idle Problem

[Swann, Benjamin R. (BSWANN)]

[I've been fiddling around with a high idle problem on my '88 5KSQ for a
while.  I also had what I thought was an unrelated exhaust leak right near
the oxygen sensor.  The exhaust leak was repaired at a garage yesterday, and
when I picked up the car, the idle problem was immediately improved.  Hmmm.
Anybody think the exhaust leak could be related to the high idle?

Could it be that the exhaust leak did not allow the O2 sensor to do its job
properly?  And that this closed system, when it has a failure, defaults to a
signal that tells the ISV to idle high???]

I've seen this happen.