A temporary cure frequently is to speed your idle up by a very small amount (less than 50 RPM usually does. Haven't been worried enough about it to see if it's mounts or something else, but mine is like a massage chair at idle. If you literally just speed it up 20 or 30 rpm off that idle point to a new one (with the ELR) the vibration dampens and becomes a non-issue. Just a dynamic thing I guess. I haven't even left mine ELR'd up, I just let it rattle when I'm alone and keep a foot lightly on the accelerator at lights when somebody's riding with me and objects.
That said, replacing bad mounts is good practice even if there are work-arounds
