i would remove and clean the IAC. it is the cylinder lookin deal on the front of the TB. clean the TB out as well. reinstall and check your idle settings (the stop screw, TPS, etc), and run it.
if the ISC went south altogether, you might have to replace it - worth trying to clean it first. you can test the values for it as well.
there are other things, but those are the biggies. good luck.