Thanks all of you,

I was breaking my head down when I change the optocouplers I used (MOC3021 - 23), some of them didnt worked very well, because the firing pulse were too short, so I inc the pulse time and put the right optos, and now I get about 100 times less flickering (some flicker at 5 sec interval), but I think that I can wash my code and get rid of this.

Gabriel