I think the leak is coming from the black heater hose connector, I've changed it before but put it back on in the wrong order .I should've put it on the metal pipe then into the fire wall connection, instead I put on the opposite and struggled with it after that I seen a few drops from that connector...although I haven't seen any drops from there recently I have a sneaky suspicion that ,that could be the issue cuz it drops directly onto the manifold. I just can't see any trace of coolant anywhere else.