MPLAB-X has its own simulator with quite a steep learning curve but it's worth the effort. It seems to be more fussy about configuration register settings than the real life chip. Occasionally PORTA seems to be incorrectly simulated with some pins failing to set.

This example repeatedly toggles all the PORTA and PORTB pins on and off apart from RA5 which is input only.

Simulating the code while watching the special function registers and user-defined variables can often explain why a program is not working as expected.

Video Guide - 5 Minutes

PIC16F88 Assembly Code Example for the MPLABX Simulator

; ---- EXAMPLE CODE ---- TOGGLE PORTA and PORTB pins in the simulator - Please watch the video.
#include "p16F88.inc"
 __CONFIG _CONFIG1, _FOSC_INTOSCIO & _WDTE_OFF & _PWRTE_OFF & _MCLRE_OFF & _BOREN_OFF & _LVP_OFF & _CPD_OFF & _WRT_OFF & _CCPMX_RB0 & _CP_OFF
 __CONFIG _CONFIG2, _FCMEN_ON & _IESO_ON

RES_VECT  CODE    0x0000            ; processor reset vector
    GOTO    START                   ; go to beginning of program

MAIN_PROG CODE                      ; let linker place main program

START:				    ; INITIALISATION
    bsf	    STATUS,	RP0         ; Select bank 1.
    movlw   b'00000000'		    ; Set all port pins to output / Disable ADC / Set for digital i/o
    movwf   ADCON1		    ; Disble ADC module (Never leave this to chance)
    movwf   ANSEL		    ; Set analog i/o for digital i/o (Never leave this to chance)
    movwf   TRISA		    ; Set porta - RA5 is input only so this bit is ignored
    movwf   TRISB		    ; Set portb
    bcf	    STATUS,	RP0         ; Select bank 0.

MYLOOP:
    ; Toggle all port pins ON (except RA5)
    movlw   0xFF
    movwf   PORTA		    ; RA5 is input only
    movwf   PORTB
    nop
    nop
    
    ; Toggle all port pins OFF (except RA5)
    movlw   0x00
    movwf   PORTA		    ; RA5 is input only
    movwf   PORTB
    GOTO    MYLOOP    

    END