In a medium bowl, combine 1/4 cup cilantro, 2 tablespoons lime juice, 2 tablespoons olive oil, lime zest, chili powder, cumin, salt and pepper.
In a gallon size Ziploc bag or large bowl, combine chicken and cilantro mixture; marinate for at least 2 hours to overnight, turning the bag occasionally. Drain the chicken from the marinade.
Preheat grill to medium heat.
Brush chicken with remaining 1 tablespoon olive oil; season with salt and pepper, to taste. Add chicken to grill, and cook, turning occasionally, until chicken is completely cooked through, reaching an internal temperature of 165 degrees F, about 12 minutes. Let rest 5 minutes.
In a large bowl, combine chicken, remaining 1/4 cup cilantro and remaining 2 tablespoons lime juice.