[Abeo]

Bump from the dead. I had this problem for the longest time, and this was one of the threads that kept coming up when I searched.

My car was slow to spoil, had weird timing retarding in boost, and had sluggish throttle response even at idle. Turns out it was the PCV valve making a huge boost leak that was being dumped into the intake pipe after the maf across the valve cover. Since the air was metered, it didn't show the typical symptoms. The PCV rattled and I couldn't blow through it ... Blocking it off while testing something else identified it.

Just wanted to add my solution after chasing this problem for a long while.

Edit: Turned out my car had a bad CAS also. Had timing scatter that was really bad after 4500 rpm, identified by a timing light while revving it up (it would jump from ~15 degrees to ~40 for an instant). The car was on the dyno and had a up and down torque curve showing the engine knocking, going on the knock map, then off, then knocking again...