Loss of Power, CEL On, Runs fine at idle...

[dirtlawyer]

I have a 1999 Boxster Non-S with Tiptronic transmission. The car has approximately 54,000 miles.

Two weekends ago while driving the car we noticed a sudden loss of power, most notably above 2100-2200 rpm. We pulled over, turned the ignition off, waited a minute or so and restarted the car. The car would rev without any problem but when we put it in D and started to take off it had the same symptoms. Luckily we were near the house so we returned home. When losing power, it seemed to sputter a bit, as if it were not getting fuel. The next day I tried starting it again (hoping that it was something simple like a computer re-set... LOL) and the CEL was on. Had to car taken to an independnet German Auto/Porsche repair facility. Talked with them this am - the fault code indicated a problem with the Tiptronic (module?).... is this a likely cause? If yes, what should I expect in terms of a replacement cost?

Thanks!