trafic 2005 1.9 lots of white smoke but ticks over!?

Hi all, just found this fantastic site hoping someone can help out in a diagnostic for my 05 1.9 trafic, as ive had a few people look at it and have had some hideous suggestions.
My van has been off the road for 6 months now and im pulling my hair out as i need to get it fixed as i still owe lots on the finance!, basically it starts fine, well after a few turns and will then tick over almost without a missed beat, but if you try to rev it it trys to increase but misfires, and a ton of white smoke pours out the back!!!, there is no apparent leaks at all from under neath.I must admit ive not been the most caring of owners and it has only had 2 services since new, now on 110K, but ive never had any trouble engine wise at all. No oil or management lights are on, on the dash either.Ive been told by various people who incidentaly have only had a brief look, that either the turbos shagged, or the whole engine is knackered, i have a little trouble beliveing this as it does tick over ok??, any ideas anyone that a hands on person like me can check for before he sucomes to shelling out over a grand for a new lump when it maybe something simplish!!, one last thing to add is that if i take of the filler cap when ticking over there is some small amount of smoke which comes out, again been told that this maybe just where the engine breathing is just choked up and needs all the filters changing, right up to the rings are shot!