Cactusbusdrvr is correct in that A/THR is very sensitive and will react to any speed decay to get back on VAPP quickly which is why it is IMPERATIVE that the T/L's are closed - COMPLETELY AND PROMTLY - at the correct time.
On a gusty approach the Groundspeed Mini function can exacerbate the problem as it is designed to MAINTAIN the aircrafts energy and any delay in getting the power off can add to that energy leading to big float. Whenever I fly an approach in such conditions I always close the levers fractionally earlier than normal to allow for this phenomenon.