You forgot to silicone the intake bolts that go into the coolant passages and have an internal coolant leak. Or if you did you may have done a poor job doing it.
I'm with
TopspeedLowet, but there could be some other issues to look at. Since it is more than likely that you will have to do the installation all over again, this time definitely check a few things so it doesn't happen again. After everything is removed and clean, simply lay the intake back down onto the heads with no gaskets and visually check the intake flange to cylinder head mating surface, if the angles do not lay perpendicular or you can visually see gaps in the mounting surface when viewed from the front or rear of the engine, the machined angle of the heads and intake are not matched properly, this can also be checked with a feeler gauge too. If that checks out okay proceed to check the coolant passage alignment
from the heads to the new intake, do a simple "dry" mock-up using just gasket strips the same thickness as your intake gaskets that will be used for final assembly. If the coolant passage alignment looks okay. Perform another "dry" mock-up with new intake gaskets this time to be sure that the coolant passage in the
intake gaskets match properly with the heads and the intake. And lastly be sure that there is not an issue with the intake bolts bottoming, as some intakes have a thicker or thinner bolt flange than others. Depending on the cylinder heads, some bolt holes around coolant passages can be blind tapped - using intake bolts that are too long is a simple but sometimes overlooked mistake, you think the bolt is tight but it has simply just bottomed out leaving the intake not sealed. Also don't go hog wild on the silicone, please use it - it works great, but a little goes along way, some guys have a tendency to go crazy with that stuff. I use just a little on my finger and go around both sides of the gasket mounting surface. If it's literally squeezing and oozing out as you are tightening things down, it's too much! There should only be a small bit of silicone visable after everything is tight and you should be able to wipe it clean with little effort, not an entire roll of paper towels.