Above 3 is almost always an installation problem. It is highly likely your insulating washer on your antenna mount is installed upside down, crushed, or missing entirely.
Posted this week in a thread about this exact thing in this exact forum...
The insulated shoulder washer is a nylon piece that separates ground from hot. It is essential that it is installed properly.
If your mount looks like that, though, you likely have no bond between the mount and Jeep because of paint, removing paint from the contact area will resolve that (but a quick way to check that is clipping big jumper cables, not the 'emergency kit' type, to the frame and mount - improvement means the mount has no/inadequate bonding).