01 auto transmission ground problem

I have an 01 2500 Cummins with an ATS stage 1 transmission. I have had problems for about a year now with the torque converter not staying locked up and continuously kicking in and out like it is slipping. I have done my best to diagnose the problem and i think that i may have narrowed it down to be a ground problem, since it seems to stop for a week or so every time i clean the ground that is attached to the block. i eventually after cleaning this grounding spot several times decided to replace the entire ground cable and that seemed to fix the problem for about 3 weeks and then it was back to the same old stuff. i do not know where to go from here and was hoping that someone may know some sort of solution any ideas would be appreciated. thanks