Right, so yours won't have an idle control valve. That pipe is VERY known for splitting, it's the oil breather pipe and with age and use they go brittle. The best way to fix is it buying a new pipe (A VW Dealer will rape you for it though), or buy an used one without any cracks or breakages from ebay/scrapyard/forum. As I said, they are very common for breaking and leaking so be weary (also when fitting a new one as it can break easily). Them broken can affect our idle, it may be rough and the cabin may smell of hot engine oil if the leak is large.