update: the sam and fuse has been thoroughly inspected today, and the mechanics found no faults on them.
there's an extra info from the owner, that a couple of months before, the ecu had been remapped by a UK firm. the nest suspect, according to the guys at the shop is a faulty remapping process had some how caused the program in the eprom to be missing.
has anyone had the same problem here? anyone experienced in ecu remapping, especially on mercs of the 203's vintage?

chippeduk