Assuming the car is not turbocharged, the hose should run to a flame trap on the plastic flexible intake duct near the throttle plate. The hose or flame trap might be clogged or there might be an air leak. To check the flame trap, remove the large and small hoses and twist it out. It is a bayonet mount. It is plastic and may not be very durable. I clean mine about every 2 years or 30000 miles with solvent and put it back in.

Also, the sealing ring under the oil filler cap can dry out or crack leading to loss of oil.

All this assumes the engine does not have serious wear or a mechanical defect causing excessive blowby. As a quick check does the engine idle differently if you remove the oil filler cap when it is running, or do you feel a lot of pressure if you put your hand over the oil filler neck?