have you had a compression test done? know what the numbers are? the symptoms you're describing sounds like they may be unrelated.
if you want more power, why not just install a nitrous system? if you're planning on doing a bargain-basement job by just installing a turbocharger (without an intercooler, oil cooler, bigger injectors, stronger valves, reinforced/shielded exhaust, etc.), you'd be lucky if the motor lasts another 20k miles.
i'm not trying to rain on your parade, and if you could pull it off it would be great. i'd just hate to see another porsche get trashed because it's been 'performance modded' ricer style.
edit; read this thread for the proper way to do a turbo conversion. note how much time, money, and parts it's taking and the car's still not finished;
http://forums.pelicanparts.com/showthread.php?threadid=282050