It could also be your EGR cooler. Park the rig on a decline, pull the egr valve and leave it parked like this overnight. (This is a good time to clean the egr valve
In the morning, check the bottom of the hole where the EGR valve was for the presence of moisture. The soot inside should be dry packed powder. If the soot is greasy feeling or you see any indication of water, your egr cooler has failed.
You would then need to
A: stop driving the truck, or you will have head gasket issues
B: Flush the cooling system
C: Replace the oil cooler and egr cooler (or delete the egr cooler if you can)
If that checks out as not being the issue, try a new degas bottle cap from Ford. When the caps go, they can allow the coolant to puke a little.
Another thing to be aware of is that the coolant level on the degas bottle is wrong. When cold, the coolant should be about 1/4 to 1/2 inch below the add line.
To check for popped head gaskets:
Get a pressure gauge installed into the small coolant line that returns to the degas bottle from the intake manifold. The pressure should not go above 16psi. If it does, your head gaskets are toast.
You should return the tuning to stock when tracking down problems. Once it is all figured out and running right, go back to your preferred tuning.