What would cause engine oil to leak into the air flow system? on 1999 Dodge Intrepid

We just bought the car today and were told that water pump was going out, so we started taking it apart to change that and found oil in the air flow system. Now we are at a loss and don't know what could cause the problem or how to fix it, or if it even can be. Any help you can give us will be greatly appreciated.

Asked by for the 1999 Dodge Intrepid
Faulty PCV system.
I agree with ziptie
We cleaned it out and it hasn't done it again... the thing that confuses me is that the oil level wasn't low. I think the people that owned the car before us were even more oblivious than us when they did the work on the car. Replacing water pump now and hoping for the best!