Started rather strange. My idle would hunt whenever the car was warmed up.
A quick search pointed me toward the possibility of upper clutch switch (a bitch to get to) being faulty. Shifting into gears while the car was stationary confirmed that.
The idle would jump to 1200 or so when I'd shift into gear (with the car not moving), and jump back down to 1000 whenever I'd shift back into neutral.

Replaced the upper clutch switch, yet the idle would still hunt, surging to about 1200 or so, and staying there.
Upon buddy's advice I changed out the engine temp sensor (back of the block), and the idle is back to normal.

Didn't have to play with ISC or IAC.
Hope this helps.

Peace!