Think of it this way: The throttle body is the main gate controlling airflow into the engine. The IAC valve is a smaller valve *adjacent to* the throttle body, fine-tuning the idle speed by controlling a small amount of air bypassing the throttle plate. They are essentially a unit.
To locate them precisely:
1. Open the hood.
2. Locate the throttle body. This is a large housing with a butterfly valve inside, connected to the intake manifold and the air cleaner. You'll likely see a cable connected to it (the throttle cable).
3. Look closely at the throttle body and its immediate surroundings. The IAC valve is usually a small, cylindrical component directly attached to or very near the throttle body. It may have electrical connectors attached.
Because the specific location can vary slightly depending on the engine (the '92 B250 came with a few engine choices), a visual inspection is the most accurate way to find them. Consult a repair manual specific to your van's engine for a diagram. A quick internet image search for "[Your Engine type] 1992 Dodge Ram B250 IAC Valve" might also yield helpful visual information.
