Please read the datasheet, in section 9.1 you can see the configuration bits, you need to set the the FOSC bits to 100, which means INTOSC with RA4 and RA5 as IO pins... the internal oscillator works around 4MHz...
please refer to your Development IDE and Programming tool to see how to program the Configuration Word onto the PIC...
BTW I suggest you to keep RA3/MCLR as MCLR Only!!! some programming tools can't reprogram the PIC after changing that configuration