When the car is cold, the O2 sensor is disabled, so the idle is open-loop. Any air leak in the idle circuit (or other issues) will cause driveability problems. If it smooths out when warm - i.e. when in closed loop - this just means the engine management can somewhat compensate for the problem, e.g. enriching the idle mixture to compensate. Rather than suspect the ICV, I would look first at hardened, cracked, or leaky hoses/connections in the idle air circuit.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7