Cylinder 3 is misfiring and when the car warms up it doesn't want to start again.. Do you know what's wrong?

Just recently put a new head gasket in, water pump, plug wires, and spark plugs.. Also tested the spark on cylinder 3 and it sparks in the plug wires.. The car doesn't die, it's just when I restart the car after it warms up when it won't start again until it's cooled way down..