Rough Idle

run a good fuel system additive through it, like BG or Lucas.

Tristan/Heanorboy, yes I have been considering putting a additive into the tank and will do this week as the van is getting a few wee jobs done.Research so far puts Archoil AR6400-D the one to try.Will post result later this week. Thank you for your replys

Might be as simple as a fuel filter change to make a difference,

Follow up to my "Hunting"engine condition. Was recommended an additive named "Comma" a lot of taxi drivers use this so purchased (£5) and considered a slight improvement,however spoke with a mechanic friend who produced a additive called "Forte" only available to the trade,this is an all singing/dancing additive and did improve overall performance and no Hunting. I think an additive used every so often cleans and keeps your engine clean. Many thanks to all replays and suggestions.

When was it last serviced?

I'd try the potions the lads have just recommended first, but if they don't work, I'd check the following:

Air filter. When was it last changed? If it's dirty, change it.
When did you last get a fill of diesel? Was it just before the problems started? Did you fill up in a reputable mainstream garage?
Diesel filter. If it's clear plastic, check for white emulsion in the filter. If there is a drain, empty it. You may have moisture or dirt in the diesel.
Throttle body. Take it apart and clean it but only if you're confident with mechanical bits. There may be carbon build up preventing the valve from fully closing.
MAF sensor. The only way to know if this item is goosed is by plugging a code reader and read the fault codes. These can be bought quite cheaply on ebay these days.
Wiggle all of the sensor plugs. Seriously, this has worked for me in the past!

I have a 2012 transit for work and so do a number of colleagues. I have had this happen and a fuel filter sorted it, others have had the ERG valve replaced as they have gummed up.
Hope this helps