Hi take a look at both your exhaust manifolds especially the last ports on either side the 5.7 like to break the mounting bolts off flush with the cylinder heads and will (tick) leak when cold and when the manifolds heat up expand enough to seal the leak...the bolts my still be there due to the heat shields holding them in place look for black leakage spots or have someone start the vehicle while you listen at the wheel wells...if there is any broken bolts the manifolds will need to be removed (more bolts will break this is guaranteed to happen ) and all broken bolts removed from the head and all new bolts and gaskets heat shields replaced and the manifolds checked for warpage ...the other issue your having is possible thermostat sticking or a small air pocket behind the thermostat that has settled there while standing over night check for any signs of leaks around the water pump area and check your level with the engine cold if level and no leaks I would replace the thermostat and bleed the coolant system and check for the same symptoms when cold