Power Steering Pressure (PSP) Switch
WARNING: This page is about a different car, the 1995 Ford RV Cutaway, 1995 Ford Econoline, 1995 Ford Cutaway, and 1995 Ford Club Wagon. However, it is still accessible from the selected car via links, so may be relevant.
The PSP switch monitors power steering pressure and signals PCM to adjust engine idle speed under load conditions. Switch is located in high pressure line from PSP pump to steering rack assembly.