Sorry to insist, but SONAR in 2.0.37 was perfect.
Please have a look to this video. This is using 2.0.37, defaults PIDs and the behaviour, I consider almost perfect.
Same hardware with 2.0.38 is really much worst and oscillating. Maybe it could be re-consider to come back to the 2.0.37 philosophy.
Noise problems are ALL solved isolating and shielding cables to SONAR and separating from ESC (as recomended in the WIKI)