Citroen Berlingo engine manegment lite is on permnetly& air bag light too

Could be anything best to start with a code read to see what's stored.unless there's an obvious misfire.

When i start van it sluggish and sometimes cut out but not everytime it seem since the wet weather

Itis sluggish when start and have to give it some revs then iidle ok

Basic things to do are remove clean or replace plugs clean leads and water proof with WMD 40 and clean out throttle.

get your battery checked out. sounds like a voltage issue

For the sluggish / idle problem , check or replace engine coolant temp sensor which lets the ecu know how much fuel is needed i.e more fuel on start up from cold and then leans out as engine heats up .