My 1999 3.0 stopped working this morning. Failsafe engine mode message and red light so the engine just cut all power, although the engine was still running.

I was lucky, I was on a quiet road and was able to come to an orderly stop out of harms way.

Has anyone experienced this in heavy traffic, on a motorway say? If I had been doing 70MPH in the outside lane of a busy motorway what might have happened? I couldn't drive and ease my way off the carriageway, I just lost all engine power immediately. On a busy motorway what are the chances that I would have been rear ended?

It strikes me this is a very unsafe function. A warning light with "STOP" in large red letters would have a similar effect without stopping you in potentially a very dangerous situation.

 

Anyone want to but a 1999 3.0 V6 S Type. Perfect condition, no known faults .

This may or may not help you but I have had a recent issue with my 3.0L V6 2006.  First occurred last March limp mode came on, no handbrake, ABS, Cruise and engine management lights all on.  Cleared itself after an hour or two apart from the EM light which remained on for a while.  I googled it at the time and found two threads of use - one relating to a weak battery and one the throttle position sensor.  I replaced the battery the next day (it needed replacing anyway) and then the car was fine for a few months (don't think this was the fault though read on) until returning from holiday in September and the same thing happened on the M25 - fortunately I was in the inside lane and it was late at night so not much traffic about.  This time I merely wiggled the connecter for the TPS and bingo!  The car started with no warning lights immediately.  The following day, I pulled off and on the connecter about ten times and sprayed it with a liberal application of contact cleaner before refitting.  I then used a high quality silicone grease on the outside of the sensor to repel moisture.  Since then it has not missed a beat.