Cutting out

I have a 3.9 v8 1993 disco 1 and it runs nice BUT sometimes it just looses power and dies all I have to do is switch it off lock it and unlock it and it will start fine and run until the next time I think it is the immobilizer but I have no idea were to find it or how to bypass it can you help. I do have a good bit of mechanical common knowhow but this is a line I have not tried before and I know that you boys have the knowledge.

Would suggest a post in the Discovery section. The alternative is try and get appropriate wiring diagrams but wouldn't know where you'll get those.