I think it may be the little block of foam located in your main air filter housing.
Open your air filter housing and take out the air filter. In the back corner of the housing is a little retangular box. (A hose clamps onto it from the outside.) There are two tabs holding the cover on the little box. Take the cover off, and there is a little block of foam in there.
Purolator refers to it as either a Crankcase Ventilation Filter or Breather Element.
Purolator Part Number B15064
My Haynes manual refers to it as a "Positive Crankcase Ventilation (PVC) system filter".
You may be able to clean yours. Mine was too far gone so I replaced it. Cost me $2.00 for a little chunk of foam. If I can find some packing foam with the same density that's what I might use next time.
I hope that is what you need to know.
Take care.
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'98 Contour - Zetec - ATX
91500 miles
Just bought her.
