^^ Are you sure, did you do a compression test and check your results against the specs in the manual for your engine?
White smoke can be fuel or steam from coolant. Smell the exhaust and see what it is. Your problem could be plug wires. To test plug wires, use a household cleaner, or a spray bottle full of water. Start the engine when it's dark, spray down the plug wires, and look and listen for the spark. You should be able to see flashes in time with the miss in the engine on the plug wires if you have bad plug wires.
You can also test for spark leak by turning the AM radio to a place where there is not a station and listening. You will hear a pop through the speakers in time with the miss in the engine.
Best wishes, but generally if you need a head gasket you'll have coolant mixing with the oil, or coolant leaking into the combustion chamber. If you're not missing any coolant, and there's no peanut butter substance in your oil, then the head gasket is likely to be ok.