After Injector reinstall engine runs rough or misfire

1994 Xjs 6 cylinder ,
injectors were removed , cleaned, stray pattern checked , new o-rings and filters , #1 was replaced with a reconditioned one. , All injectors are D3155ka by ucas . New o rings feel looser, since the old ones were stuck one from age . Now my engine runs very rough at idle at 900 rpm. at higher rpm is gets smoother.
what can this be ? gina .

There is a remote possibility that one injector is intermittently not firing at idle speed. I have seen this happen exactly twice in 18 years of servicing injectors. And I think it was with this Lucas injector. Difficult to diagnose without an o-scope or having the injectors flow tested on a machine that can simulate idle operation. You might also try disconnecting the injector harness connectors and trying to clean the injector electrical pin contacts, although that is probably better done with the injectors removed. SD Faircloth

thank You , yes 2 fuel injectors were bad, passed smog ! gina