I had a problem with an inconsistent miss on idel, and found an easy solution in this situation.
I bought a can of throttle body cleaner. I removed the ISC and sprayed inside the holes until all the black deposits were removed. I then ran the car at high rpm, and sprayed it directly into the manifold intake. I than sprayed it inside the PCV valve hose and ran the car again.
Took it for a drive, and it was smooth as a baby’s butt.
Luke N has done a similar process on his car.
CAUTION: Slippery When BOOSTING!