Sounds like the IAC (or is that the iak you mentioned?) -- the IAC is the idle air control solenoid. It's adjusted with a pulse width modulated signal to control the idle.
Either the PCM or the IAC could be having a problem. OR, the MAF perhaps. Intermittent failures of the MAF don't get detected and reported very well. On my '02 3.0 liter I can disconnect the MAF and the first code I get, and only after a couple of minutes, is that the intake air temperature sensor reports bad and not the MAF.
Without a code, it's tough sometimes. Have you reset the PCM? Disconnect your battery for 15 to 20 minutes. Now reconnect it and start the vehicle and let it idle for 15 minutes without driving it. This will force the PCM to relearn the idle air control strategy and though I don't think it'll solve the problem, maybe it'll help.
Any pinging or knocking when it surges?