Hi Mike and welcome

Hi,
     My 1999 MV6 had a similar problem. It turned out to be the Mass Airflow Sensor. The analogue output signal drifts up and down when the unit gets hot. This has the effect of making the mixture ratio go out of limits and the engine loses power or stops.
   The engine management computer is still receiving a signal from it, (albeit erroneous), so it does NOT light the engine management warning on the dashboard. It will log a fault code by comparison of other sensor inputs, which can be read with a fault code reader.
   A secondhand MAF sensor is about 60 - 100 quid and a new one is about 280. Bosch are aware that these thin-film type sensors have a limited lifespan, but have done very little to correct the problem.

   The crankshaft sensor on my car has just failed, so I will be joining you in the "oily hand" gang this weekend.

   Have fun.

Hello & Welcome