Check engine light is on?

Hey my name is brittany I have a 2002 mercury sable Gs I been exsperiencing problems for the past 2 months my engine light has been coming on and I felt alot of jerking I had replaced my plugs and wires also my hub assemblys and had got a new air filter and did a gas treatment for the past 2 weeks I have been smelling fuel when I turn n my heat in the mornings wen I put the gas treatment in it stop now for the past week my check engine light has been blinking instead of just being on so I took it to a machanic he say its a misfire in spark plug number 6 also when I press on the gas my car is alil hestitate can you tell me whats the problem and how much is it goin to cost to fix wheather it be coil pack to fix etc

There was heavy raining tonight and I went through two deep puddles and my engine light started flashing. The light itself is always on because my threads are stripped in the first cylinder. And when I got home, I noticed it was smoking white slightly under the hood but still noticeably smoking. Anyway. I have been letting it rest for about thirty to forty five minutes, the smoking has stopped, but the idle is rough, acceleration is poor and slow and the light still flashes. Any ideas? Does it maybe just need to dry out?