If you experience difficulty starting the engine when cold, stalling at idle, or hesitations during acceleration, it may be the idle air bypass valve. This valve helps the vehicle idle steady when the accelerator pedal is not pressed.Google+
Car Problem Reports
Ford Crown Victoria Problem With Idle Air Bypass Valve May Cause Engine Performance Problems
Ford Crown Victoria Problem
Engine Affected: 5.0L V8
Average Mileage: 176,500 mi (100,000 mi - 253,000 mi)
Visitor, 1999 Ford Crown Victoria, 253,000 mi
air idle control went bad. Hard to start an idle n cold .
did not fix it yet cause i just found out what was causing this when i got on here but yes ,hesitate when taken off ,also hard two strart, also ruff idle.