How do you change spark plug 1991 Toyota Previa?

To change the spark plugs on a 1991 Toyota Previa, first, disconnect the negative battery terminal for safety. Remove the engine cover if applicable, then carefully detach the ignition wires from the spark plugs, noting their order. Use a spark plug socket and ratchet to remove the old plugs, and then install the new spark plugs, ensuring they are properly gapped. Reconnect the ignition wires and the battery terminal, and ensure everything is secure before starting the engine.