This 14 pin (Ground Cap) plastic connector that brings all the ground wires together. I had one of the connections in there that melted part of the 14 pin ground cap just like yours.
I cut and removed all of the ground wires from the ground cap and crimped round eyelets onto the wires, then used 2 brass 10/32 bolts to join all the eyelets together.
Sorry never took a picture of my round electrical connection eyelets all together on the 2 brass bolts.
This also fixes the same problem, see post 65 on this link.
I had the same problem on the way to NatStoc in 2012. The dealer near Omaha Nebraska found a major connection in the wiring harness had fried, melted. The place in question was below the throttle body. I saw it when they replaced it. The stealer also said there was a recall on the harness in...
www.st-owners.com