Mpu9250 Gyro Unstability

Hello everyone
I am working on a project; using mpu9250 on stm32f4 discovery board.
I am trying to configure PWR_1 register and clock source but it does not work.

I do the following :
disabling sleep mode ; writing 0x00 to PWR_1
wait(100 ms)
choosing clock source to one of pll sources ; writing 0x02 ... 0x05 to PWR_1

after such a configuration i have still unstable gyro values and a wrong temperature value.
Any Idea?
thanks