Quoting number936:
It was kinda weird, with the car in diagnostic mode or whatever (pin 10 grounded), we threaded the BISS fully closed (like 3 turns) and it fixed the surge and idled steady at 1400rpm. After shutting the car off and starting it again it idled super low and we ended up backing the BISS out a turn or so. Not sure what was causing it to idle high at first with the set screw bottomed out...
When you ground #10 it sets the ISC at the center of its travel, then you adjust the BISS to get idle "close" so the ISC has plenty of room +/- to adjust for coolant and air temps, AC, etc.
Give the ISC some time to learn the new idle/BISS setting ( it will rather quickly if in good shape ).
Also you checked the resistance of the ISC coils? Make sure it's good else the ECU drivers will fry in a heartbeat.