* Reduced engine performance: The engine may run rough, lose power, or be harder to start.
* Oil leaks: Increased crankcase pressure can force oil past seals and gaskets.
* Vacuum leaks: The PCV system is part of the engine's breathing system. A blockage can disrupt the vacuum, potentially leading to other vacuum-related issues.
While a severely clogged PCV valve *won't* make the engine suddenly rev high, the resulting issues *could* indirectly lead to erratic engine behavior in some scenarios. For instance, if the increased pressure causes a vacuum leak in a way that affects the idle control system, the idle speed might fluctuate. However, this is an indirect consequence, and a revving engine is usually symptomatic of something else.
In short, a clogged PCV valve is more likely to cause poor running and reduced performance than a sudden increase in RPM. If your engine is revving uncontrollably, you should look elsewhere for the cause, such as issues with the throttle body, fuel system, or ignition system.
