That sure looks like a Frankwire job. It did not come from the factory like that for sure.
It's definitely something electrical. That's why it's worse when it's raining. Something that should be insulated is not, and the water is acting as a conductor to make it even worse.
Now we just need to narrow down the possibilities starting with the cheapest fixes first.
I'd unwrap all that black tape and check the wire connections to make sure that they aren't corroded. Someone obviously tore apart the split loom around the wires and wired something up..... Possibly a new pigtail connection for the coil. They may not have done a good job insulating the wires or protecting them from the elements. Electrical tape alone won't cut it.