1998 Idling ruff and I need ideas 2 fix,

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I have a 1998 (150,000miles} with a 5.7 engine that is idling ruff and the starter has to turn over a long time to start the engine when warm. When cold it starts normally. The engine light is not on and I checked for a code but none found. I replaced the plug with AC Delco. I am old school and not sure what else to replace. I am going to do the wires and rotor cap next, but what else should I replace? Thanks Dave