Where do you locate the idle air control valve on a 2006 Lincoln navigator engine?

The Idle Air Control (IAC) valve on a 2006 Lincoln Navigator (with the 5.4L engine) is typically located on the throttle body. It's a small, usually cylindrical, valve mounted directly on or very near the throttle body itself. You'll find the throttle body near the intake manifold, at the top of the engine.

To be precise: You'll need to look closely at the throttle body. The IAC valve might have a single electrical connector plugged into it. It's a good idea to consult a repair manual or online diagrams specific to the 2006 Lincoln Navigator 5.4L engine for the exact location and visual identification since there can be slight variations.