Sorry for the delay, I had some issues getting back on the forum.
My router has been running just perfectly for such a long time with the current settings I thought that even though everything moved freely, it wouldn't hurt to take it all apart and clean it. Well, along the way I discovered that one of the set screws that locks my X axis to the shaft was loose. It was the one that tightens against the flats. So, under load the pulley would slip, but under normal operation the other set screw held it tight enough that there was no slack.
Still it wouldn't hurt to have you look over my config and see if there is anything you see out of wack.
Mach 3.043.063
XBox Plugin
MSM Professional 2.0
Dell Optiplex 755 (Two Cores, 2Gb ram)
Onboard video
Onboard Parallel Port
PMDX-126 MultiMode Breakout Board
PMDX-133 Gecko Motherboard
Gecko 203V Drivers (current limited to 5amps, 117.5K resistor)
Kepco 350W power supply (48V, 7.5Amps)
Z-Axis 20000 steps per inch, 160 Velocity, 30 Acceleration
Standard .1 pitch lead screw, direct drive
Xylotec 2.8A, 269oz
X-Axis 15875 steps per inch, 120 Velocity, 40 Acceleration
Metric 10 Pitch, 2/3 belt drive,
Xylotec 2.8A, 269oz
Y-Axis 7620 steps per inch, 180 Velocity, 40 Acceleration
Metric 20 Pitch, 2/3 belt drive
425az, 4.2v, 3A Stepper from HobbyCNC