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.

hi jim

had similar problem with my v8 3.9L not long ago she would start no problem then once i blue moon she would appear to loose power and just die on me. she would start again after a few mins and run fine.

changed dis cap and rotor arm and new plugs and shes not missed a beat since.

hope it helps