Likely you haven't found the 'sweet spot' yet. That one little spot where nothing moves. Likely it'll be a bunch of micro adjustments to find that spot.
Also, if you haven't already, set always sync to 1. That might help.
<edit> Ok, I see now you mean set "-alwayssynced" correct? I thought you were just using bad grammar!
("..., set always sync to 1. That might help.") I read that as, Set, ALWAYS, synch to 1. </edit>What does the synch set to 1 do? Is that in Arcadeos, mame, or both?
Do you mean vsynch?
-vsync/-novsync (default: -novsync)
Synchronize video display with the video beam instead of using
the timer. This option can be used only if the selected video
mode has an appropriate refresh rate. Otherwise, MAME will
refuse to start, telling you the actual refresh rate of the video
mode, and the rate it should have.
If you are using a tweaked mode, MAME will try to automatically
pick the correct setting for -vgafreq; you can still override it
using the -vgafreq option.
Note: the 224x288 / noscanlines mode doesn't work on most cards.
Many games use this mode, e.g. Pac Man and Galaga. If it doesn't
work with your card, either turn scanlines on, or don't use
-vsync.
If you are using a VESA mode, you should use the program that
came with your video card to set the appropriate refresh rate.
Note that when this option is turned on, speed will NOT
downgrade nicely if your system is not fast enough (i.e.,
gameplay will be jerky).
-alwayssynced/-noalwayssynced (default: -noalwayssynced)
For many tweaked VGA modes, MAME has two definitions: One which
is more compatible, and one which is less compatible but uses
frequencies compatible with -vsync. By default, the less-
compatible definition is used only when -vsync is requested;
using this option, you can force it to be used always.