HELP! Sudden Power Loss!

[2002 Black Box]

Help! My 2002 Boxster S w/Tiptronic is exhibiting some troubling behavior. For the past 2 mornings I have left my home and driven for aprox. 10 minutes and then began to experience surging in the engine before it completely loses power. When the power loss occurs the engine rpms drop to 1000. Further, I lose all throttle response. Thankfully I have been able to limp to the shoulder, turn the vehicle off for aprox 5 minutes, restart the car and no issues for the remainder of the day...
WTF? I am throwing a P1503 code, but cant seem to determine what this is..

Any thoughts????

[BYprodriver]

I'm not familar with that code either, but I bet either your fuel pump is going out, or the crank position sensor. Has this happened while you had at least gas tank 1/4 full? Do you know when the fuel filter was replaced?

You don't want your car exibiting bad behavior, STL cops may shoot it!

[Timco]

Other car makers use that code for throttle position sensor issues, but Porsche does not list it. Are you 100% sure that's the code? Did you read it yourself?

[2002 Black Box]

Read code on Accutron tool...

Tonight the engine was surging badly revving between 600-2000 RPM...

Full tank of gas and never below 1/4 tank

[2002 Black Box]

Ok... Found an explanation for the code...

What the heck is the Throttle Jacking Unit and how do I check it?