Avman
Thanks for the reassuring words, however I'm sure this one was different to the scenario you describe. We were mid-cruise and there was no change in altitude for a number of minutes before or after so I do not think that it was simply descending.
The 1st time it was midway through the pilot's PA to pax so again it wasn't too busy at the time.
And lastly it was definitely only 1 engine which dropped it's speed right back - and the immediate directional change which was almost as quickly corrected also seems (to a mere SLF) to indicate a thrust imbalance betwen the two engines.
However the same KLM Fokker must be still flying as it hasn't been in the news since that they made a smoking hole anywhere, so it was obviously a non-event. But that didn't help me at the time.
Steve