Our 560 SLC has a rough idle that we are unable to correct. So far we have:
Replaced ignition wires
Checked distributor cap
Ajusted air flow
Substituted idle relay
Checked for vac leaks in all injector areas
Seems to be on the #3 cylinder. Symptom changes with running - when warm it runs better than cold. Uneven running, or miss, goes away when reving to beyond idle speed. We have had this problem with other models also, for example in 420 engine.