Ignore that service manual stuff since you can actual read your IAC counts.
Since you're reading ''0'', that means the ECM has commanded the IAC to close as far as it's mechanically able. That mean one, or both, of two things. Either your throttle blade is open too far and passing so much air it took the IAC port out of the loop. Or, you've got some crud between the IAC pintle that's leaking unwanted air into the engine.