[Shotimes] Surging at idle

[Christian Kesselring]

Car did something interesting today at lunch.  I noticed a strange noise
while cruising, but thought nothing of it since I had the climate control on
auto and it could have been the heater engaging and disengaging.  Then I
noticed that whenever the car was in neutral, i.e. at a stoplight or
cruising to a stop, the rmp's would climb to ~2k for 1-3 seconds, than
settle back down to ~900.  It seemed to coincide with coming to a stop, so I
thought it was something to do with that function that raises the rpm's in
neutral at speed to facilitate shifting into gear.  But, when I parked the
car I waited for a minute and observed that the surge ocurred at ~10sec
intervals the entire time.  Then, after lunch, I got back in, started up,
and it failed to repeat the strange behavior.  I have noticed that seemingly
since the weather turned cold, the car has had a little more of an unsteady
idle, but it has only ranged from 800 - 1100 rpm.  Hmmm...I will have to see
if it surfaces again, but what could cause this?  All I saw in my previous
digests was a suggestion to check the ISC(Idle Speed Control) or something
like that.  Please help.

Christian Kesselring
'92 SHO 119k
'02 PT Cruiser 9k