matt,
i had htis code flash up when i did an ECU diagnostics and the reason it comes up is that there is some sort of fault with the ECU getting readings from the knock sensor
in my case one of the 2 knock sensor's was not plugged in!
it could aslo be that the sensor if faulty or just screwed.
it takes 2 minutes to check them: just stand over th battery looking towards the throttle body. If you hold a torch and look through the intake runners of cylinders 1 and 2 then you should see a little green sensor with a white plug plugged in. It is right under the intake plenum and attached to the block (may be hard to see). there is also another snesor between runners 5 and 6. have a look. in my case the plug's were hanging and not into the sensor... i had many of the symptoms you mention above of which most went away after i put the plug back in!
cheers,
Warren