While driving, car grinds to a halt, engine stops

Summary

I have narrowly and frequently just missed head on collisions from an intermittent fault with the car and am now afraid to use it at all.

How long the problem has been present

Problem has been occurring intermittently for a year and a half, with each part replacement being accompanied by a "the car is fixed" statement from the garage,

Summarized symptoms

While driving, car grinds to a halt, engine stops, trying to restart finds no electric power, no sound when turning the key, sometimes the radio will work but everything else is dead.

Other symptoms

(1) Average waiting time before car will then start (with the key) six hours.

Or can be jump started straight away and sometimes can be driven away normally but other times may require a number of hours before power returns to the system.

(2) The breakdowns occur regardless of whether the car is hot or cold.

(3) After recovering from breakdown (.E.G via jump start) car will start every time, first time, until the next breakdown.

Frequency of breakdowns in distances driven (most recent first) has been:-

Five hundred yards
Eight miles
Three miles
Fifteen miles
Two miles
One mile

Periods of time in between breakdowns (most recent first):

Five minutes
half an hour
Three months
Two months
Two weeks
One day
One hour

Parts replaced:-

Battery (brand new)
Alternator (almost brand new)
Coil packs
Plug leads
Plugs
Crankshaft Sensor
Ww motor

Parts tested:-

Battery and alternator (multi-meter) all in order.
Engine computer management (garage computer) no faults found.
Main engine earth (cleaned).
temperature radiator sensor (all in order).
fuses (inside car) no faults found.
Starter motor.


Annual ministry of transport tests (MOT's)

Flies through every year for the last six years.

Responses from garages and mechanics so far:

1. We have checked the car thoroughly and can find no fault.

2. We have done everything we can but can help you no further.

3. We have not a clue what could could be causing the breakdowns.