using mach 3 when on cnc mode  rpm is about 200 less then actual if i try to go up speed goes all the way up to top speed

Could be many things depending on your setup. First thing however would be to go to the macro folder then the folder of your profile and delete the Linearity.dat. Then start Mach and see if it  is ok.
If not attach your xml and a description of your spindle setup.
Hood