So Im coming over from the dark side..naza flight controllers, and have purchased an Iris and an 3dr x8. Not impressed with the loiter mod lock on either one. running factory PIDs and feel that the lock up on gps could be better. Altitude hold in loiter sucks..deviates 3 ft sporadically. My nazas and wookongs held much better. 

Any good PIDs out there to stop the wandering. And yes everything is calibrated as per 3drs suggestion.

any help is greatly appreciated.