I have a P reg 1997 petrol VW Sharan. I also had a problem where driving through a puddle would result in complete loss of power.
Had the coil pack replaced and this has cured that particular problem. If you have this problem keep a can of wd 40 in the car, and spray everything in the vicinity of the coil pack until you can get it replaced.
I found after a spray the car would start and I could continue my journey
Steve
April 2011