I have a 2008 charger with the 2.7l, it runs fine when you first start it but when you shut it off and restart it I get a misfire on cylinder 4 I have changed the coil for cylinder 4 same results any advice would be greatly appreciated. Thanks

 

New coil will ensure a solid capacitor to ignite spark; but if the plug is in poor condition and the fuel injector has carbon buildup around the port it will produce the same symptom. What's the mileage? Have you had an injector clean? Plugs?

 

Not to scare you but in past FWD applications the 2.7 was notorious for weak head gaskets. If you have an internal head gasket leak, once the engine reaches operating temperature the head gasket will expand by thermal dynamics and weep coolant into the combustion chamber. Once you shut the car down the coolant will continue to weep until the metal in the engine compresses the gasket (stopping the leak). When you start it up there is coolant there that will foul the plug until the coolant is blown out of the combustion chamber. But hopefully this is not the case...