I am new here on this forum.

I own a 2000 Mercury Marquis LS with 70000 miles on it. I purchased it used.

I have been experiencing a problem recently since the weather has gotten colder, below 50 degrees, that when I cold start my car in the morning, after it has been running for a few minutes, a sound like an air raid siren starts to eminate from the engine compartment.

After I drive away, the noise disappears, and I do not hear it again. When the engine is warm or hot, and I start the car, I never hear the noise.

I placed my ear against the air filter housing, and it sounds like it was coming from inside along with a vibration.

Everywhere that I have read so far on the internet suggests that the culrpit is a defective IAC Valve.

Have any of you experienced this with your Crown Victoria's with the 4.6L, and what did you do to remedy the problem?

Suggestions are appreciated. Thanks.