Have you done throttle body coolant bypass? Two things it could be, first the two large coolant hoses that go into the firewall or if bypass not done there is a hard line tube that runs behind the engine and is coupled to another by a 3" piece of 5/16" hose. You can see it with an extendable small mirror and a flashlight but can't touch it unless you pull the transmission. I had to replace it on mine, you won't smell coolant but if you notice even a drop or two behind the oil pan that's what it is. Hope not