Check the threads for the spark plug, Im betting it was either crossthreaded or not tightened enough and worked itself out.
There would be six spark plugs for a six cylinder engine. One for each cylinder. Unless it is a diesel, then there are no spark plugs.
I'm not a mechanic / technician but it might be the spark plug , spark plug wire , not the proper air / fuel mixture to that engine cylinder , and there are probably other causes
sounds like a cylinder misfire..check spark plugs and wires..usually a code will show which cylinder it is, should replace all though
Most likely a bad coil (each cylinder has one) located at the top of each spark plug
Bad spark plug, bad spark plug wire
i would try changing the spark plug first
Spark plug, plug wire, distributor cap, injector, internal engine ........as in a blown head gasket.
Replace the spark plug wires. Also, be on the lookout for something that could cause a lean condition such as vacuum leaks and fuel flow restrictions.
bad spark plug wire.
Engine missfire. Cylinder #4
Faulty: spark plug, spark plug wire, ignition coil, ignition module, fuel injector are the most common. Coolant leaking into a cylinder is another. Internal engine problems such as burnt valve, broken valve spring, bent push rod, worn rings
When you say fire I assume that you are saying that there is not spark, if so then the answer would be that the rest of the car is running off the battery.