That looks like coolant leaking from the metal water bypass tube at the 90-degree bend as it goes into the intake. You can't see it now, but follow those exact instructions you referenced, and when you lift up the lower plastic plenum shell you'll see the pipe with the hole in it. Some have welded it, but most just replace it. It's about $32 online or $65-$70 at the dealer.
Motorcraft part # KM4386.
https://www.amazon.com/Motorcraft-KM...ag=scubacat-20