Citroen Relay cutting out under load?

Have above van 2.2HDi 2004 (FSH). Van cuts out when under load, is alright first thing in the morning when cold. Once warm it cuts out (sometimes just limp home mode) at anything over 2000rpm. Engine management light comes on & will restart after a few seconds. Management light goes out.

Fault codes are 191 & 404. Have had low pressure fuel side checked, new filter, and high pressure pump checked. All OK, but HP pump needed calibrating. ECU values check out OK.

Anyone any ideas?

Ta