Well, i think i solve my problem.
I have a 78L05 well regulated output with a 10nF ceramic capacitor between +5V and GND, also i also have flyback diodes across inductive loads.
What i did was to increase a little bit my MCLR pin with a diode. (likely the cause was the MCLR pin voltage decrease a little bit), I saw in datasheet and Voltage on MCLR with respect to VSS can go to +13.5V. Also, put a 10nF cap between Vss and GND (near my PIC).