I have a 2002 Sebring Coupe with the 3.0L engine with a P0300 code that has be at my wits end.
Prior to the following work I had an EGR code with an occasional misfire. Car ran fine other than MEL light being on.
I have done the following to fix;
Replaced the wire, plugs, cap and rotor, intake manifold gasket and new valve cover and tube seals.
After starting I now have a P0300 misfire code with a rough engine idle. I also have what I will call an occasional backfire (but it is more like just a dead cylinder exhaust noise, its a muffle sound) really not sure.
I have rechecked all connections and for vacuum leaks. Plugs wires are all tight. The car starts right up with no delay.
I am stuck and the wife needs her car back.
I need help. What am I missing?

Thanks, Dennis