Hi,
The idea is that, immediately after turning off the ignition, you press down the accelerator about half way and hold it there for a few seconds. This means that as the engine dies it sucks in clean air.
The explanation for why this works is here:
http://www.fordwiki.co.uk/index.php/Cold_Re-starting_-_Mk3 . Note that on my car like many others, this issue can occur even when it's stopped once fully warmed up. So, best to press the accelerator as described every time you stop.
Seems a very common issue which, presumably, Ford could fix if they fancied it.
MarkSpace.