The Valve end of the IACV (called the Idle Air Control Valve) does not move when you take it out, and don't try to move it. The IACV is a small servo motor, and you are right, that is a threaded shaft. DO NOT connect it to the plug and power it up,out of its housing, or you'll be wondering where those parts flew off to.
The MAF (mass airflow sensor), Fuel Temp sensor and TPS (Throttle Position sensor are the three main culprits to a rough running engine (no, not the O2 sensors, they only tell the ECU to enrichen or lean out the mixture) You can easily check the TPS, and it's best done with a conventional meter type VOM (volt ohm meter), not the digital one. There are specific voltages you can check for at the 3 pins, but the simplest check is a resistance check, looking for a smooth rise (or fall, depending on which end or the resesitor you are checking. You need to connect one probe to the center (wiper ) contact, and the other probe to eother end of the fixed winding,then look for a smooth meter movement, with no jerks, or points where it drops then climbs as you move the armiture of the TPS. When a TPS goes bad, it is almost always at one of two spots on the sweep of the TPS wiper contact; at the rest point (where the engine is at idle), and at the throttle position where you would be at cruising speed.
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