I have many issues with mode 6 on PCjr on Dosbox.

Space Quest 3:
Dosbox freezes if CGA 2 colors is selected on PCjr mode.

Rambo 3:
The song is hear but no picture if CGA mono is selected.

I have no problem with Qbasic and Pc Gammon.

Rambo 3 and SQ3 run fine on real PCjr with mode 6 used.