When trying to start my car, it can take up to 20-30 seconds for it to fully start. After it does start, white smoke comes out for a couple of seconds. Then there is a puffing type of sound like pa-pa-pa. Along with this I can smell gasoline. Also the engine independently revs; I am not pressing on the gas pedal. What is causing all these problems and what are the solutions?
White smoke out the tailpipe is usually a sign of coolant leaking into the exhaust or cylinder. This is usually caused by a blown head gasket, cracked cylinder head, or cracked engine block. It will also cause a misfire similar to what you describe. Have a professional mechanic such as YourMechanic do a compression and coolant leak test to determine if you have one of these issues before further damage is done.