2002 Mercury Sable • 72,000 miles

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
January 18, 2013.

Scan for codes and check fuel pressure first

Jan 18, 2013.
It could be the coil or many other things. Has your mechanic check the coil? Did he replace the plugs?