gav525 wrote:

Nope, I'm back at work for a month so haven't had a chance yet.

When I get home end of March it'll be getting a post winter service and a few other wee jobs so will look at it then and see if I can figure out what's up.

I had similar issues, engine would cut out if you press gas in neutral and rev it, and revs would drop too low when shifting between P,R,N,D. This all sorted with cleaning of the throttle body.
The easiest way to clean it, is to put ignition to position ''on'' with engine turned off, and have somebody to press gas pedal (or put the brick or some stick on the gas pedal), this will open throttle flap.
Then brush it with the help of old tooth brush and brake (or better throttle body) cleaner.
All the residues will come out because of the throttle body position, so it is good to put some towel under it.
This is procedure that I used on mine AJV8 engine.
It is also good to clean maf with some maf cleaner. RR HSE 4.4 2006 LPG