Did you fully wipe before flashing 4.2 ?
Give cyanogenmod a try first.
And explain how the "app not working" goes for you.
Like you start getting force closes? which app exactly you are trying to enter into?
LG Optimus G
MOKEE OS (Android 4.4.4)
Motorola Atrix 4G (Puchased another digitizer, taht thing was #$%$ed up too.) Retired in the closet
Self ported MoKEE 4.2.2 (Based on CM10.1 epinter 20131211)