This was originally posted by Nogo a while back on LS1tech
Here are some things you can try.
Idle Limiters --> Idle Speed: 950
Idle Limiters --> IAC Park Position: Raise all points from 40C and up to 21
Idle Limiters --> Idle Air In Gear: All points 60C and up to 8.6
Fuel --> Main VE Table: Multiply column 400 rpm by .60. Multiply column 800 by .80. Multiply column 1200 by .90.
Ignition --> High Octane Table: Add 2 deg to all points 400 to 1000 RPM, .08 to .32 g/sec
Once done with this program, start the car and check for surging. If the car surges, unplug the IAC and see if the surging stops. If the surging stops follow below.
Idle Limiters --> Idle Air in Gear --> All points above 60C to 9.2
Take the car for a drive and check your idle. If the car goes on cruise control reduce the Idle Air in Gear Table .2 (further if necessary). If the idle holds at 2000 RPM for extended periods of time reduce the P/N Airflow Decay table for all points above 10 MPH by 5% (multiply by 95) until this stops. Be vary careful on this table.
If car keeps surging with the IAC unplugged two more things to try.
Multiply Main VE table by another .95 (which would be a total reduction of 85%). Repeat until the surging goes away, or until the car begins to hesitate when you take off.
High Octane Ignition Table. Reduce timing for all points 400 to 1000 RPM, .08 to .32 g/sec by 2. Repeat, but don't reduce it any more than 6 degrees.
If your car still doesn't idle after this, then you have other problems, and should start looking elsewhere.
Its not perfect & idle tuning is not always cut & dry but this has always been a very good starting point for idle tuning.
Feel free to add you .02 as to what has worked best for you guys, but try and keep the thread on track with the same type of information.