Vauxhall Combo 1.3 cddi smoking

[dnarra]

Had this issue for a while, it will drive fine idling around 700rpm no smoke. Then for no reason the revs will pick up and sit around 950rpm, it will pour grey smoke and stink of fuel, if you are driving and look in the mirrors you would think it was on fire there is that much smoke! No warning lights and no loss of power. Van is a 2007 with 60,000 miles (original). Took it to garage and they recommended I change the EGR, a genuine EGR was fitted and made no difference at all. They then suggested it was a faulty injector, changed the four for recons and still no difference.....Getting desperate now, please help

No fault codes at any time!