MPU6050/DMP Intermittent bad data output?
Looks like the major driver in the data 'noise' was the FIFO data rate, set via the MPU6050_DMP_FIFO_RATE_DIVISOR constant in MPU6050_6Axis_MotionApps20.h.  I changed the rate from 100Hz (0x01) to 20Hz (0x09) and got the following almost completely noiseless plot under the same conditions as before.  Note the vertical scale - only 6 deg total, and the one 'excursion' is only a 4 deg change. I also plotted the 3-point running average, which further reduces the excursion to less than 2 deg.

So, if you are looking for clean yaw (Heading) data from the MPU6050 DMP, consider changing the FIFO rate.

Frank