Van losing power when cold

[Darbs]

T25 1.6 td 1990 , van starts ok then I drive for a couple of minutes pull up at junction and lose power ,sometimes it stalls .Power comes back then it happens again when I pull up at lights junction etc a few minutes later however it doesn't happen after that? I've had fuel filter changed and additive put in fuel but it's still happening, any ideas? Thanks for looking

[jason k]

Are you using the cold start lever???