Cat 315B Stick Function Bogging

Hello all, I have been working on a Cat 315B that will intermittently bog down heavy with the stick out function. I have checked, cleaned, and resealed the control valve already and have repacked the stick cylinder, but no change. I would go after the pump or the PRV, but it only happens with the stick out function. I'm looking for a few pointers from some of you who have possibly dealt with these before. Thanks!