Erp asked if the readouts reflect the slow down and speeding up and the answer is yes they do follow the speed changes.  Vincent

Then it's a software issue, probably your mach configuration.

Have a look at your CPU usage when this happens (Ctrl Alt Del)

Hood

I very much doubt it's a CPU issue doing this, to just slow down the parallel port driver only during a direction change would be very unusual.
I think it has to be an issue with his Mach configuration, assuming he's in inch mode? an acceleration of 5 or 16 should be noticeable, but not drawn out. I assume the slowdown/acceleration is drawn out?
Maybe he has something weird set in backlash compensation?
Is there any other setting that directly affects speed/acceleration?
How long does it take to change direction? full speed to full speed?
You describe the steppers as stalling, this is something very specific when talking about steppers, can you elaborate on what you mean by stalling?

The motors say Deepgroove 3.3 v,2.8 amp, 1.8 deg. , 280 oz.

[Rant] I really wish sellers wouldn't do this - I doubt very much that deepgroove make their own motors and if they're going to publish anything then at least publish the FULL specs.[/Rant]

Yeaaaah. ERP got it. I had the backlash set wrong. When i disabled it, it worked great. Now I can start setting my machine up correctly with limit switches etc. Guys, thanks for all who replied. You know, it makes you feel stupid to find such an easy fix but I guess thats how it is when you dont know. Again, thanks,    Vincent