I would just search the forum. With over a million HEMI's out there, I am sure someone has had that issue. Sounds like you may get a new motor as they rarely open them up for repair. I assume under warranty and in the dealers hands? It is not MDS lifter related, as that is Cylinder 1, 4, 6 and 7. Maybe a head gasket as they are side by side?
So far I have had over 100,000 miles of personally driving HEMI's with no major faults, and overall the vehicles have had 239,500 miles and had never been opened up or had as much as an oil leak. Yes to a timing chain recall, alternator (self), a PCM that needed resealing and connector cleaning (self), a water pump (self replaced), Spark Plug replacement (self), an oil pressure sending unit (self), a few belts, and a crank position sensor (dead of winter, I had to pay a garage). All but the recall were on a 2008 300 C. Zero issues so far on 2013 and up HEMI's
Good luck and please keep us posted on the repair process and dealer involvement.