Land Rover Repair: Speedometor flucuation, engine management computer, speed sensor

Question
I recently purchased a used 1997 Discovery SE7 with 107,000 miles, and a couple of times on the expressway doing roughly 60 mph,it stops accelerating and the speedometor drops to 0 mph and starts spining back and worth, only for a few seconds. Could it be a tune-up problem, a transmision problem or a power loss issue?  

Answer
Your speedometer is driven by a speed sensor on the transfer case.  That same sensor tells the engine management computer how fast the truck is going.  If it scrws up it can cause the needle to swing and the engine to cut out at the same instant.

That's where I would look.