PIC 16F887 and the mysterious System Clock Select bit (SCS)
You don't need to also write the SCS bit if you already selected the internal oscillator in the Configuration bits.


  bit 0 SCS: System Clock Select bit
  
  
  1 = Internal oscillator is used for system clock 
  0 = Clock source defined by FOSC&lt;2:0> of the CONFIG1 register
  


The SCS bit is 0 by default, so the system clock is selected by the FOSC&lt;2:0> CONFIG1 bits.

You don't even have to set the IRCF&lt;2:0> bits, because their reset value is 110 = 4 MHz.