2000 Dodge Durango idle

Suspect a vacuum leak. Listen near the vacuum hoses while the engine is running, or pinch them off, one at a time. If you find one that brings the idle speed down when you pinch it, follow it to the leak or to where one splits off. Pinch each one of those to see which one to follow to the leak.

There can also be a leaking intake manifold gasket. To identify that, run some water over them while the engine is still cold. You'll see it get sucked in or the engine will slow down momentarily.