Rough idle

First, I have changed plugs, wires and coils tested good. New fuel filter and injectors were removed and cleaned. After inspecting valve train I found a rocker arm off and lying in top of the head. Reinstalled . (bought car two days ago, valve stem top looked good and everything in valve train looked normal) The car has a miss at idle but runs perfect on acceleration and at highway speeds. Any idea what I need to focus on? there is one vacuum line off from the intake to the throttle body but its plugged on both ends. the rocker arm was on the intake valve that cam off. no backfiring to indicate intake valve issue.