We bought a 1999 Galaxy last week. It was to be. For a couple of days when we would buy dog food, the engine stopped suddenly, we got started it and went home, it stayed a couple of times on the way home.
Once home, I opened the bonnet, then I discovered batterits negative terminal set fully loose and rattled!
Could it be the reason that the MCU has received a problem ??
Start starter goes as it should, but no spark !!

/Bertil

Yeah if the battery is loose it breaks the electrical connection, this can very easily lead to the car stalling, the question is, why did it come loose?

Have you checked the battery terminals to make sure they are not corroded?

I thought they'd made a sequel to Space 1999 for a minute there...  

Loose battery terminal can definitely cause your problem, should be an easy fix though.  

if I'm reading correctly, the starter turns but no spark? It ain't loose battery terminal then. 

That terminal does need sorting though. 

I assumed starter tries to go but never starts fully, but poor voltage and connection is something I experienced from a poor connection.