Can anyone help me? I was just flying MIA-ATL. Nearing FL480 (Cruise Alt), I noticed my IAS falling bellow 240. I checked autopilot to see if I had changed it from the 310knts I had orginally entered after passing FL010. Nothing worked, so I diverted to an airport I found in GPS, making an emergency landing. The aircraft, once off autopilot, was very erratic and out of control. I was able to calm it before landing, but I was off the RW due to the weird flying. Does anyone know what happened? All help is appreciated.