I assume you have a factory fitted immobiliser fitted to your car? If you have this could be the answer, it is quite common for these imobilisers to cut out whilst driving, it also happens to late granadas as well. Quite frightening at 70 mph lol.
When it happens again, see if the warning light starts flashing in a unusual way, this is a fault code and will point you in the right direction. The fault is caused by a solder joint on the fuel pump relay which overheats. The imobiliser is located under the heater housing.
Hope this helps
Steve Eastman, February 2005
