Help rooted but cant gain access on some apps!!!!!

I rooted my Micromax Bolt q324with kingoroot pc software successfully but after a few days i cant able to get root access for some apps like when i install a new root app it asks me for permission then i tap grant but the app shows unable to gain root access. how to fix this issue i tried flashing my phone with stock ROM then again rooting it with kingoroot but again no luck i was unable to gain root access for some apps but when i check root access with root checker it says root access properly installed and i can go to terminal with root access but when i try to mount system as rw it shows ''Mount: operation not permiited" how to fix this issue!!!

And yes the phone is a spreadtrum sc7731 chipset device so the rom file is in .pac format but i figured that how to flash it.So i am willing to install a Custom ROM if you provide me the link of it.......

from xda-developers http://ift.tt/1P6g4Jx
via IFTTT