Engine stalls

[AndyR]

Hi folks. My Astra has developed an engine stall. Starts up fine and runs reasonably well under power. But as soon as you back off power to come to a stop, the engine cuts out. 

I didn't think an automatic would do such a thing, but yep she is. I have changed plugs and coil pack. No difference. It does sound like there is a bit of a misfire on tick over. 

Any help or ideas would be greatly appreciated.  

TIA. Andy.