You may need to get some softer dampers. My E5 has a little bit of a wobble below 1750rpm head speed, that being said I haven't spent a lot of time at that head speed so it may be FBL controller induced as well. The other thing to do is put in a bit more expo than you're used to especially in your "normal" or "mode 1" (whichever you are going to use for hovering)and leave it how you normally have it in your next flight mode(for the flying maneuvers). If you can separate the pitch curves out between flight modes I would also go and add in the flight mode used for hovering and flatten out the pitch curve 1% or 2% around the 3/4 stick point or where your hover point is on the collective. These are the tricks I've used in the past, there may be more trick out there that I don't even know about. I hope this helps.
