Freelander 2 HSE i6

Hi, I have an intermittent fault with my 2007 petrol engined Freelander 2. Sometimes when starting, it fires up OK and then just dies after a few seconds. If I rev the engine quickly, it generally keeps on running, but it's really bloody annoying. Anyone had a similar problem and knows what the cause is? I'd be grateful for any help. Thanks.
Sandy.

All FL2 engines seem to dip in RPM, a second or so after starting, my TD4 does it, however it doesn't stall. I'm not sure exactly what causes it really. I did wonder if the Immobilizer handshake takes a few milliseconds to complete, allowing the engine speed to drop. I also considered it could be the alternator is suddenly taking huge amounts of engine power just after the start, and the ECM can't quite keep the RPMs up.
In short, I've no real idea.
However on the I6, it would be worth checking the throttle body is clean and free to move, and make sure the plugs are in good order too.