[Vwdiesel] Bad Starting

[Iain Hunter]

Hello.

My name is Iain Hunter and I live in the UK. I drive an '85 Transporter (vanagon) with a stock 1.6 TD engine. Recently, as the weather has dropped below freezing, the van fails to tick-over once started and usually stalls shortly afterwards, even under throttle. Even if I manage to keep the engine running, she cuts out as soon as the motor is placed under any load. It's as if the engine is running on 3 cylinders. 
Up until the cold weather, she has been absolutely fine and has started and ran without any problems. Is it possible that an injector has just suddenly failed without warning, or is it more likely pump timing?
I realise that this engine was not offered in the U.S, but as far as I am aware, it is the same motor as offered in other models that were. I would appreciate any help on the matter.

Cheers.

Iain.H.