I had the same problem and symptoms on a Hemi with those same MP heads. I finally pulled the valve spring off an intake valve and was able to move the valve side ways .004" .005". The guides were way too loose. These were a new set of heads too.
I would think that Modern would catch this on your engine though as that is who fixed mine.
Once the guides were repaired all was good. I have been told the factory guides are oversize and soft.