Happy New Year!!
I've been looking forward to returning to this thread to post my own solution to this 'window-smashing' capacity of a car problem. You can add my MK 3 2.0 8V GTI to the list of vehicles with faulty crank angle sensors!
I got an auto electrician to come out with his VAG system to pin point electrical faults - there were 4 on my car! Lambda sensor, crank angle sensor, mass air flow sensor and hall sensor. The hall sensor on a MK3 is part of the distributor, so I replaced it with one from the scrap yard - but didn't stop the cutting out. Then replaced mass air flow sensor - engine idling nicely, but still cutting out. Got a used crank angle sensor off ebay [seem to be a steady supply of them on ebay] for £20. It wasn't actually that hard to replace, you do have to remove the front engine mount and starter motor to get the alan key at it, you don't need to remove the oil filter as it says in the Haynes. The car is running perfectly now and I'm confident about driving distances again!

I haven't changed the lambda sensor yet, but will do when the exhaust system needs replacing soon.
Hope this helps someone out!
All the best!
Jonathan