2000 Citroen Xsara rough running

With car of that year , better going to breakers yard and getting injector rail / injectors and replacing .

Injector open circuit has nothing to do with plugs or coils.
If you unplugged an injector and ran it that would flag an open circuit code.
An open circuit is either a broken wire/s or faulty injector.
No current flowing.
So as the previous respondent stated get S/H injector/s but keep in mind it may be the wiring or injector connector plugs.

Car is only doing it when being driven but ok when ticking over and engine is cold

Go back,
which injector is open circuit?
Codes should have stated that.

Dosent say which injector

Get it scanned with "Lexia" Citroens own diagnostics and it should.
French cars often if not always scan better on their on make of diagnostics.