I had an almost identical problem on mine (P reg v8 auto). It stalled started after a rest a couple of times but would then only get half a mile or so before stopping again. It was apparently an immobiliser problem which a local independant landie mechanic (and rib nut) sorted out by bypassing it. PM me if you want me to try and get hold of him for more detail.
Mike
pm'd
I have tried this angle but have been told (not main agent this time) that the immobiliser can't be bypassed on this model due to various electronic guff they spouted. Most of it goes over my head - all I want is the bloody thing to work - no more comments about jap stuff etc please - I know already!
A couple of questions.
1) Does the engine a) just stop, or b) does it splutter a bit first?
2) Does the rev counter a) still read as you grind to a halt, or b) does it read 0 rpm immediatly?
Answer 1) a and 2) b - probably an electrical fault.
Answer 1) b and 2) a - probably a fuel supply fault.
I am now getting worried, I have TWO imobilisers fitted to mine. The satandard LR one and a Cobra.
__________________ Mark H "A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools" Douglas Adams
A couple of questions.
1) Does the engine a) just stop, or b) does it splutter a bit first?
2) Does the rev counter a) still read as you grind to a halt, or b) does it read 0 rpm immediatly?
Answer 1) a and 2) b - probably an electrical fault.
Answer 1) b and 2) a - probably a fuel supply fault.
I am now getting worried, I have TWO imobilisers fitted to mine. The satandard LR one and a Cobra.
Answer:
1) a) it just stops
2) a) reads sometimes but generally drops
That probably means that it has fuel and electrical faults or just that there's another sympton yet to be identified - great!
If the rev counter is slowly dropping with engine speed, i.e. the engine is still being turned on over-run, your ignition is still live. Therefore the immoboliser is not cutting the ignition.
I now suspect it is fuel related.
I has something similar on a RR Classic when the wires to the fuel pump were packing up.
__________________ Mark H "A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools" Douglas Adams
Manufacturers have gone to great lengths to make cars un - nickable - it has got to the stage where they now break into people's houses to steal the keys.
Joyriding is dying out - Swansea is the capital of joyriding - one of the places I go mountain biking is where they dump all the stolen cars - the sort of cars nicked are things like old astras and golfs etc - evn saw a Volvo 240 estate the other day - REALLY scraping the barrel - they just can't get the new cars away.
Of course the trouble is when the electronics go wrong - as they do on ALL new cars - ever heard of a computer that doesn't crash???
Jon hopefully this helps you, most problems we come across in boats, cars engines etc, usually usually are simple fixes, its just knowing where to look, wasting all the time etc etc.
You have to try and decide is it fuel, or is it electricial
can you tie it to any particular time or instance
Would it be difficult for you to hook up a remote fuel tank and breather
try to rule out things if possible
bypass your filter for a day or two and use an inline one, drive with a temporary fuel filler cap in place with a drilled air hole in it.
I accecpt that it will be difficult to bypass the factory immobliser, but not an aftermarket one like in an alarm system
carry a volt meter and when it stalls check to see if you have a voltage on the coil contacts of one or other of your main relays, if the fuel pump is electronic check for voltage here, again when the car is good, and when it stalls so you can make comparisons etc
The satandard LR one and a Cobra. 
