Mau
Could you send me a pic of your ground point? I think I used the same. Picked up a new amp and same issue. It seems like it happens most frequently on the highway when I'm on cruise or at speed not gassing it.
I picked up the ground in the back of the trunk, left side. There is a factory ground point available right on the floor tucked in the corner. I didn't do anything with forscan. Just wired, set the gain and done. Trunk rattling bass.