Had a similar problem on my V8 Disco. I could be a dry joint in the immobiliser supplying the power to the coil.
When it stalls again, get a multimeter and check the power supply to the coil, it should read 12 volts. If it doesn't then run a temporary power wire from the battery straight across to the coil. Your rangie should now work again. For a permanent repair, run a new wire from the ignition to the coil (bypassing the immobiliser).
Vince
January 2011
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