How and when does the engine cut out? Does it cut out when you stop, such as approaching a junction, which would be better described as 'stalling', or does it cut out without warning when you're doing 50mph on a straight road? These symptoms are entirely different.

In that case the engine is stalling, and yes the throttle body and idle speed control could probably do with a good clean. It would also be a good idea to remove the EGR valve and clean that too. Make sure it opens and closes fully and doesn't stick.

Once you've cleaned and refitted the idle speed control valve, which is a stepper motor, switch the ignition on and off a couple of times, leaving a short pause each time. This will enable the motor find the correct position so the the engine idle speed is correct. Then start the engine and allow it to idle. If the idle speed to too high or too low you may have to repeat the procedure. It should idle at around 850-900rpm.

I'd go along with what Hardway says. Crankshaft sensors on these are inductive pulse, and a very common issue with them is the cable breaks down especially where it bends. The sensor can be checked easily with a multimeter for resistance and AC voltage output. But if you're in any doubt it's best to just renew it as they can and do fail. They produce an anologue signal which the ECM cannot read. They only read digital signals and reference voltages based on a 5v supply. So your CAS signal has to be converted from anaolgue to digital. This is done inside the ECM. As Hardway says, the ECM is incapable of telling the difference between the engine stopping due to an unschelduled loss of CAS signal, or for any other reason why it might stop, including you switching it off.

You should understand that fault codes will only be stored when the computer is either not receiving an return voltage that it knows it should be, or when one has gone out of limits for whatever reason. This means that the computer may not necessarily see a fault even if one clearly exists. This is not easy to explain, but is something you need to get your head around. A computer is a dumb machine. It does EXACTLY what it's programmed to do. Nothing more, and nothing less. It cannot think, apply common sense, predict what's around the corner or anything else. It does what it is told. To even begin to start diagnosing faults using specialist equipment you have to train yourself to think the way the ECM sees the system.