You'll need to have a mechanic replace either the PCV valve or its connecting hose depending on which is clogged. If you ignore this problem for long, you will waste money because of poor gas mileage and worse, the overly rich air/fuel mixture will likely damage the catalytic converter. In a situation like this, some mechanics may offer to replace several other items related to the above. For now, just stick with the replacement of the PCV valve and its hose. This should correct the problem. You can always return at another time for the other items the mechanic suggested. To check for oxygen sensor issues, take this vehicle to a garage for a scope-based diagnostic checkup. The mechanic will hook your engine up to a scope analyzer from which they should be able to tell if the oxygen sensor is the culprit. If so, have it replaced