[Shotimes] 89 SHO Stalling When Going from High RPM to Low

[Scott McNamee]

Hi All,
   
  Long time since I've been back on the list. Last time I was here, Don Mallison, Doug Lewis, Josh Texiera and others were contributing..........hope they are still around. :-) It was always a great list back then. 
   
  My 89 continues to run (mostly well), but has recently run into a stalling problem when coming out of gear and coasting to a stop. Tach goes down to 500 rpm or less and either stalls or bounces back up to 700-900. This issue does not seem to occur when simply stopped and reving the engine. My suspicions are either IAB/ISC or Throttle Position Sensor, the latter having been changed twice before since I've owned the car (1994). Removed the IAB/ISC sensor last night and though it had some dry black sooty residue, it did not appear to be clogged. The pin inside the larger half of the sensor appeared to move in/out freely. 
   
  Anyone with similar problem and if so, how did you fix?
   
  Thanks!
  Scott