[jhv48]

Did you replace the plugs?
Is it one cylinder misfiring or all of them?
Pull plug wires one by one while running and isolate misfiring cylinder. Swap plug to another cylinder and see if misfire moves to that cylinder. If so, it’s the plug.
If not the plugs, wires, distributor, coil, carb, alternator, pull the offending cylinder’s valve cover and rotate engine manually to check valve operation. Could be a valve failing to open.