So it appears you DO have a intake leak, there is a passage there for coolant from the head so if the red arrow is the area of the leak then it is probably leaking at that gasket you could try putting a wrench on the bolts closest to the leak on the intake and see if there loose but if no go then the intake is coming off, not a terrible difficult job but not something you want to necessarily take on at this point. For reference the thermostat housing is bolted to the intake with two bolts directly under the upper rad hose so NOT your leak.