[Al Skierkiewicz]

According to the schematic doc on the First website there are three capacitors (C4-C6) on the board that limit the bandwidth to below 200 Hz. On the off chance that one got by without these inserted, have you checked the board to be sure they are in place?
Noise can easily be generated by loose electrical connections. Be sure all your connections are tight at PD, in and out of the speed controllers and any other electrical connectors you are using. Look also at the path your signal wiring is following. Does it pass by the wireless access, a sidecar or around the CRIO? A simple move to a different path may be all you need.
Lastly, have you insulated both the accelerometer and the CRIO? Sneak current through the robot frame will introduce noise as well.