The PCV valve cover has two long spindly plastic support "tabs", one on each side (a total of four tabs).
See this diagram if you need help visualizing http://autorepair.about.com/library/faqs/bl958e.htm , it's the blue part (#2), although the diagram has the tabs much shorter than they actually are, and there are two tabs per side, not just one per side as the diagram shows.
In the process of removing the MAP sensor module I busted one of the four tabs. The MAP sensor seems to sit on it fine still. Would that be enough to cause a leak? And if so, would that give a P0401 EGR Flow Insufficient code? That's the only code I get.