[center]First thing to check is the base ignition timing. If this is wrong, the engine will 'pink' and the ecm will not allow it to rev high.
Other than this, it will be the hall effect sender that is at fault (attached to the side of the distributor)
Your local VW place or tuning gargage shouldn't charge you More than £30 to set base ignition timing and check for fault codes.
I know that this subject has caused some contraversy in the past, but this method really does work to cure this fault!