Hi, my '96 1.4 is doing about 200-250 miles to a tank! There are no leaks, but there is a strong smell of petrol coming from the exhaust so it is obviously running rich. Does it just need new plugs & filters or should I get it tuned (can you even tune an injection engine)? I've also read about an oil separator breather box causing this problem (although I have no idea what this is).

If you haven't had new spark plugs and air filter recently, this may be a good place to start (I recommend genuine WV plugs)

It's also worth checking/changing the temperature sensor in the cylinder head. If this is faulty, it could be 'telling' the ECU that the engine is cold, when in fact it is at normal working temperature, in turn, the ECU will 'tell' the fuel system to provide a richer mixture.

An afterthought, make sure that the temperature gauge reaches normal (90degrees), if it doesn't, the faults that you describe may be caused by a faulty thermostat.

Regards.