Wierd whistling noise...

My escort has been making a loud, high-pitched whistle thats coming from under the hood. I isolated the sound and it appears to be coming from the throttle body/injector.

The noise comes and goes, you can hear when the engine is idling w/the hood closed. It appears that it only happens when the engine is cold and starting to warm up.

The car is an 89, 1.9 CFI. Any clues?

So no one has encounter this problem before? Wierd.

Have you checked to see if your air intake is plugged up or partially obstructed? Is something stuck in there making it whistle? Check the filter and filter box as well as the hoses. Maybe there is a crack in the hose causing a whistle?