Spark plugs, spark plug wires, distributor cap, and distributor rotor. If you replace all of these you would be doing what is called a major tune-up.
A regular tune-up would be just replacing the spark plugs.
You can check the integrity of the plug wires and distributor cap by spraying them with water while the engine is running. If the engine runs ruff, stall, or you see spark arcing from either the wires or the distributor cap than they will need to be replaced.
The distributor rotor always gets replaced when you replace the distributor cap.
You can also spray the coil with soapy water to see if it is leaking as well. I’m happy to assist further over the phone at
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