Need help - stalling '90 90q20v

["Solomon Ngan" <sngan@alpha.netaccess.on.ca>]

Hi,
My stalling problem is getting more frequent.
I cleaned the ISV with carbon cleaning agent.  Made no difference.  
The car just stalls occasionally at idle.  It only happens like once 
in 30 stops at idle.   The idle also tends to hunt a bit.  And then, 
all of a sudden, the rpm just drops.  If I catch it fast enough and 
give gas, I can save the stalling.
Other than that, the car runs normal.  ie, no lack of power at any 
running speed.
Any clue ?
ISV ?  
Basic engine setting ?  
Oxygen senor ?
Anything else ??
Thanks for your help.

_________________________________

Solomon Ngan <sngan@netaccess.on.ca>
  '93 100s
  '90 90q20v