sorry for the shameless plug...but are you interested in my flawless condition EVGA 6800 AGP 128 MB card ? I am selling my desktop in a week or so, and need to sell the video card too.
You can try setting the AGP speed to 4X, if your BIOS allows, also disable fast writes if enabled.
You can also try underclocking your card, by using some vgaBIOS editor(just be careful using it)