Engine code 306 on a 2005 stratus with a 2.7 engine. i replaced plugs but still idles rough.

CYLINDER NUMBER 6 MISFIRE DETECTED.REPLACE PLUG WIRES REPLACE COIL TO NUMBER 6 CYLINDER.ALSO FILL GAS TANK PUT IN FUEL INJECTIONS CLEANER LIKE GUM OUT OR PRESTONE.DRIVE CAR ENOUGH FOR CLEANER TAKE EFFECT.BECAUSE A STICKING INJECTOR WILL CAUSE MISFIRE TO THE TROUBLE CYLINDER.ALSO CHANGE FUEL FILTER. IF ALL FAILS YOU HAVE LEAKING INTAKE OR DEFECTED VALVE OR VALVE COMPONENTS.LIKE VALVE SPRINGS AND LIFTERS.

You have a P0306 . This is a misfire code. Your vehicle's powertrain control module monitors crankshaft sensor to determine the "change in angular acceleration of the crankshaft" while running. Simply put, it expects to see the crank to speed up and slow down as each cylinder fires. If the profile of the signal detected doesn't show the expected signal, a code is set.I would look into the crankshaft position sensor as the culprit. Another sensor closely related to this sensor is the Camshaft position sensor. Both are associated with the timing and how rough and smooth the idle is. i hope this helps you in figuring this out.

This code is for cylinder #6 you have a coil that is bad on that cylinder