Sorry that didn't work.....how much of a turn did you give it ? Best way to let it learn idle coming down from rpm is to let it practice. Sitting still, rev it up and let it come down over and over. When did this start ? At s/c install ? Put the throttle bodies back to where they were and start restricting the opening to the IAC. I have seen one car with a big cam that we had to block the IAC and then adjust the throttle blades for idle.......could take a combo of IAC restiction and throttle blade adjustment. One way to restrict is to use a rubber cap and start with a small hole. Sean Roe also did this post for restriction for idle hang:
Hi Everyone,
As idle hang is always a topic among stock and modified Vipers, here's how we eliminated it on a car that had no reason for it other than PCM programming ('97 GTS). Get a piece of 3/4" round stock from the hardware store (metal, wood, plastic, etc..) and cut off a piece about 1/2" to 3/4" long. Drill a 21/64" hole in it. Put this "restrictor" in the idle air control hose that goes from your airbox to your idle air control motor, on the passesnger side of the engine. Experiment with a larger hole if the idle is too low with the A/C and lights on, but this worked perfect for us at sea level. It completely eliminating the idle hang that bugged the heck out of the car owner.
Hope that helps some people out.
Regards,
Sean