Need Help! Please!!!
 

Hey gang, I drive a 2012 Dodge Charger, V8. However, for the last 3 months, I've been having an engine light problem that seems to be getting worse.

The code says my 4th piston is misfiring and I know there is an extended warranty on the head but the stealership won't change it.
I changed the coils and spark plugs; light went off for a few days but came back.
Flushed it, the next day the light came back on.

Now here is where it gets weird. About 3 days ago and again tonight after work I turned it on and the light began blinking. She made a weird sound as well but both the noise and blinking light stopped once I hit round 20 MPH

Any suggestions on what to check for or what to do? I'm starting to feel the misfire a lot more now and it shakes violently when in idle.

Sounds like an injector is blocking.