My problem is already solved but I'll relate the tale for the benefit of the forum,

2007 Cayman S , initial symptoms were:
Randomly switching off at idle in traffic,
Misfiring at higher revs (over 4500 rpm).
Occasional hard starting (turned over 3-4 seconds before firing up).

Luckily? I had had these symptoms previously on my 04 Cayenne S, so I immediately suspected the Crankshaft Position Sensor.
Suspicions were confirmed when I hooked up the PIWIS



I ordered the new part from Porsche Center Pretoria , and had to wait a few days for it the arrive from Cape Town.
Cost R2900 (about $200)

This is a picture off another website showing the sensor on the engine


The yellow arrow points to the sensor


I found a few replacement guides online so I wont repeat the process here again, but I will mention the following:

It is possible to replace the sensor from underneath the car without removing any panels, however it is extremely difficult, I found it easier to remove the engine cover
and work from the top.
Whether you work from the top or the bottom it is impossible to actually see the bolt that attaches the sensor to the gearbox. It is a T40 Torx for future reference,
once you know this, you can remove and install by "feel".
The most difficult part is actually disconnecting the electrical connector (red circle on the picture). After about 30min of struggling I enlisted help and got a friend to push the connector from the bottom while I pressed the little plastic release clip from the top.

Really this was a simple fix, total of about 1.5 Hours.

Hope this info is helpful to somebody !