As mentioned, go to the VFAQ to figure out if the ISC is any good.
You can adjust your idle with the BISS (screw on top of throttle body (might still have a cap over it if you are luckier than I)). Turning it out (left) will bring up your RPMs.
I had a similar problem a few weeks ago, but my ISC checked out OK. I adjusted the BISS to bring up the idle slightly for a temporary fix, then replaced a worn rubber o-ring on it and cleaned the throttle body. That seems to have fixed my problem.