hr minds misfire code

[srt4srsexy]

while back i got a miss fire code p0304 so i took to dealer.come to find out it was bad injectors, valve springs and valves.well 900 miles later it comes back.dealership did work.they have it now.my thing is does anyone have a idea what could be wrong with #4 chamber to keep on causing this to happen.tried new wires plugs and coil two stock and msd.could there be a crack they dont see that would cause this.any ideas or if would be great.thanks

[SLO-SRT4]

the rings might not have seated properly but I think you would have noticed that long before the miss fire.