Land Rover Repair: 1999 Disco II Computer/General strangeness, crank sensor, emergency mode

Question
Thanks for taking the time. I see you guys get swamped but trust me, we DO appreciate it!!! I have a 1999 Disco II and it's pulling 3 new and different tricks. Firstly, while driving along it will give a stutter/jolt from the engine that lasts all of about a tenth of a second. As soon as that happens the "M" and "S" lights begin to flash in unisome as well as the small red lights on either side of the "D" that the shifter is in. Once this happens the car goes into what I am told is a "limp" mode where it seems to have only 1 gear that revs really high and moves VERY slowly. I was told this was an emergency mode to "get home".

Secondly, I'll be at a light or even in park and it will suddenly rev/accelerate for about a split second. If I'm stepping on the brake it will try to lunge forward and I have to hope I was paying attention!! Again I'm completely at a loss...

Lastly, We all know Rovers in general have a personality and temprament of their own but this new trick is a real inconvenience! It starts when it wants to and and won't when it dosen't. It cranks endlessly and won't turn over... I've replaced the battery and cleaned the terminals and yet nothing! Needless to say this makes planning to go anywhere slightly difficult! I have spark because it (when it's good and ready) starts without hesitation!

Please help! I have VERY little hair left and am about to rip what's left out! Apparently after several hefty mechanic bills I finally figured out that  theres not a single rover qualified mech in my area!

Answer
All those problems could be caused by a failing crank sensor on the engine.  I've seen similar symptoms on Rovers in the Robison Service shop.  The only way to know would be to look at the live data stream with a T4 or Autologic tester and see what it shows.

You can really resolve a problem like this by tests with a multimeter as the fault is intermittent and you have to see how the computers are interpreting whatever goes on