I feel your pain, as I'm having similar problems.
-how-diagnose-resolve-engine-issues-using-durametric
It could be the MAF. Try unplugging it and go for a short drive.
If everything has settled down then you know its a MAF problem,
and a very easy fix.
Try cleaning it first ONLY with MAF cleaner spray as anything else tends to make matters worse.
Many folks get more time after cleaning but it seems that only a replacement fixes it for the longer term.
I have to admit that is sounds a lot like a fuel delivery or regulator issue but start with the easy cheap fixes first.
PS: Auto Zone will loan you a fuel pressure tester for free and its easy to test with the fuel rail Schroeder cap being on the passenger side.
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"It broke because it wants to be Upgraded
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2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)