Cat 287 loads up and stalls out

I have a cat 287 that I recently have done a bunch of work to new hydrostatic pump and sent out the 2 other pumps to get checked and cleaned. I installed pumps fired up machine had to reprime the system engine was running very rough heavy black smoke got it to idle decent. Now when i apply throttle it starts to load up then stall. I have bucket functions no drive still.