How long since a tune-up, spark plugs and plug wires, to name a few parts of a tune-up. With the engine running, raise the hood in the dark. Does it look like the great northern lights under there, fire running everywhere.
Check the distributor cap and rotor for moisture. Check for applicable trouble codes. You should be able to check mil codes, yourself. When the problem is ongoing, visually check for spark at the spark plugs. You can use a spark tester in the plug wire boot ground the tester.