I have a strange problem.
When descending long hills from a speed of 80kph or so and trailing the throttle for about 20 to 30 seconds odd, when i slow down at the corner to say about 20kph the engine falters and sometimes stops leaving me without power assist to the steering. not good.
It appears to be associated the engine vaccum.
If I throttle up before it cuts the engine picks back up and I cannot reproduce the problem without the 80kph downhill trailing the trottle part.
Any ideas anyone?

I'd start with pulling codes from the PCM and clearing the memory codes and going for a drive, reproducing the problem and then checking the codes again... It may be an out of range sensor...

Cheers,
Tim

I think it may have been a sticking PCV valve.
Problem has gone away for the moment.

Just checked the PCV valve in my FG and it is plastic. Can I replace it with a metal one from a EL or a AU?