A833 Can't Downshift / Poor Performance

I have run into this problem before exactly as you described. I dealt with it because it would not downshift to second but would 4-3 . So after about 5 years of that nonsense I had another 833 rebuilt and replaced the one I had that would not downshift to second . Problem solved. I never opened up the old 833 just put it in the shed and forgot about it.

Likely you are going to have to rebuild the trans again .