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Draco-REX
Here's were element tuning first encountered the problem:
http://www.ft86club.com/forums/showthread.php?t=73858
And if you scroll down a little on this page it talks about it briefly:
http://elementtuning.com/competition...r-wrx-fa20dit/
Again hopefully that's all your problem is.
Edit:
There was also a more recent occurance and I believe all that was needed was a new cam and rocker.