my peugot boxer has been having problems staying started first thing. It starts sound then slowly looses power and a load of white smoke comes out of the exhaust then stalls. its than hard to start but when it does the white smoke comes out and if i rev hard enough it sort of flushes out and is sound once its going. if i leave for a few hours theres the same problem ive been told it might be water in the fuel filter. Any ideas cheers