I have the same package but have not put it into service other than some benchtop testing.
The "HY" cd that comes with this kit has a pdf document on it which tells you how to setup the port pins. It from memory was not as straight forward as numbering from 1 to 8. Have a look for it and this may fix your "Y" axis problem.
The stalling of motors could well be associated with the DIP switch settings on the board adjacent to the heatsink. The above document also has info on where to set these, but you will probably find the best results will come from trial and error
Hope this helps.
Stuart