Ok Hood, I don't know how to thank you about this amazing information.
I want to bay the drivers motor but I need you to help me which driver to choice for my motors..

First thing I would do is exhaust all possibilities of it being a mechanical or motor  issue.
 I would firstly swap the motors and see if the same axis has the issue or if it changes. If it changes then it is your motor.
Next I would swap the assignment in Mach around so that X is set to the pins you have currently for Y and vice versa. If the problem stays withthe same physical axis then it is almost certainly a drive issue.

If going down the new driver route then for your setup I don't think you can go far wrong with a G504 Gecko.

Hood

As most have found out including myself, Gecko 540 is the way to go. Made in America, quality parts, great customer support including a real phone number and a website with a ton of information.

oops yes G540 and not 504 as I said above

Hood

So nice people about this information! How i saw on youtube and other source information about this driver, i can say it's the best driver around world! But it's so expensive specially for me in the beigging!
I have found other driver on Ebay that appear to me it's a good! Please people, have a look to see it, may be there are something that i didnt know about it before to purshase it!

http://www.ebay.com/itm/400858402049 

Thanks you so much!

Chinese again, may be ok, may be scrap. You pay your money you take your chance.
Having said that the stepper drives look like the leadshine drives which are normally good but again it is as above.

Hood

Hmm correct!
Thank you so much Hood!

For a few dollars more get a Gecko 540 or Leadshine... as Hood said Chinese is still Chinese. We've all been burned by the Chinese bug thinking we got a deal. I had a bad digital input connector terminal plug, the tightening screw was stripped, on my Gecko 540. Call Gecko's toll free number talked to girl that spoke English and two days later had a new one in hand, no charge.   

Hello people,

Can someone explain to me what it's exactly the option of step pulse and dir pulse? Excuse me but I yet beginner on the mach3 :S

Thanks so much!

From the manual .............

Most drives will work well with a 1 microsecond minimum pulse width. If you have
problems with the test moves (e.g. motor seems too noisy) first check that your step pulses
are not inverted (by Low active being set incorrectly for Step on the Output Pins tab of Ports
and Pins) then you might try increasing the pulse width to, say, 5 microseconds. The Step
and Direction interface is very simple but, because it "sort of works" when configured
badly, can be difficult to fault-find without being very systematic and/or looking at the
pulses with an oscilloscope.