My 95 v8 has moments like yours. Not recommended but three times in the last year I've turned her and she's not kicked off. By passed Spider long time back but still seems to be
immobiliser stoppage. On all occasions, after normal checks I have ended up pumping the fuel pedal like a demented one legged cyclist speeding down a hill. And she slowly but surely fires up. I'm thinking relay problems but that's for another day. Good luck. This is my second oldish Disco 1 and they've both been great motors. Worth a wee bit of work.
Regards. Diksdown