Welcome to the forums!
The milky residue is a common issue with those 2.0 ABA motors. Its basically condensation build up around the oil filler cap. It happens alot in the colder months.
One way to avoid this is to take the vehicle on lengthy trips as using a vehicle for short trips only will also cause the above to happen more frequently. You need to make sure the vehicle gets up to operating temperature to burn off any condensation in the oil system.
As for the engine not breathing correctly, what exactly do you mean? Did you use a vacuum gage and see incorrect vacuum readings? Do you suspect an issue with the PCV system?