Truck will get up to temp fine, then it'll hold for a while and slowly start overheating after that. I'm blowing through like 4 gallons of coolant a day, and getting a hissing from the coolant bottle and both of my hoses are not under pressure, I'm not sure if there's no pressure in the system because the bottle is empty or not. Also I have no idea where the coolant is going, I'm pretty sure it's not a head gasket issue, there's no signs of oil as far as I can tell in my coolant. Blocked radiator or thermostat is what I can think of right now but the mystery leak has me baffled. Any ideas?

 

I am sure the 4 gallons of coolant a day is an exaggeration or you would see it coming out.

First lets see what is what.

Cooling system has no pressure in it when cold
So top up radiator and leave the cap off
Start engine
no coolant should come out of rad cap opening
coolant level may should drop a bit, top it up again

If coolant does come out of the rad cap opening and continues to come out after you top it up then you do have a cracked head or blown head gasket, period, there is no other source of pressure except the cylinders.
You can do the glove test(use our search) to ID what cylinder has the problem.

Coolant in the oil or oil in the coolant "can" be a sign of a head problem, but head problem doesn't always show that way.
White sweet smelling exhaust "smoke" is a sign of head problem and also why you see no leaks on the ground, coolant is being steamed out the tail pipe.

OK, so it isn't a head problem.
While engine is warming up 2 or 3 minutes, and you have topped up rad, put rad cap back on.
Fill up overflow tank to the COLD mark, about 1/2 way on most tanks.
Now feel the upper rad hose, it should be cold, thermostat will not open until coolant in the engine gets to 185-190 degrees(takes about 5 minutes), then it will start to open and upper rad hose will start to get warm.
190-200degs is "normal" operating temp of any gasoline engine, coolant will have expanded a bit and there should be pressure in the system.
If there isn't then rad cap is bad and overflow tank should have some extra coolant in it.

If overflow tank ever bubbles you have air in the system, could just be from you not filling it up or could be from blown head gasket.

After truck is fully warmed up see if it starts to overheat again

You have the 2.3l Duratec engine, which unfortunately was designed for transverse mounting, so it has a coolant connection in the back of the engine that can leak,
You need to drop the transmission to get to it, that's the bad news, good news is you said you don't see any leaks.

 

in a 5 mile drive today i blew through a gallon and a 2 liter bottle of water. the 4 gallons is not an exaggeration, trust me. so after i got some light on it, i noticed theres a leak in the line coming from the bottom of the coolant bottle, i probably never noticed because it was happening when i was driving so by the time i parked it was empty, so no leaks obviously. it looks like its either a crimp fitting or made to put a wrench on it, i can barely see it as the charcoal canister is right there, this is just what i can barely see and feel as i reach down there. anyone know what that hose is called? or if i can cut that fitting out and just clamp a temporary hose on there until i can get the right part? id take a picture but i cant fit an ipad down there.

 

It's the overflow hose, and a leak there would not cause over heating at all and for sure wouldn't cause that much coolant loss.

That hose is only used when engine is above 200degF, and then maybe a pint of coolant would flow out of the rad and into the overflow tank.

Did the rad overflow with engine cold and rad cap off?

The overflow hose should just be held on by a spring clamp, same as on the radiator end.
Here is a look at the overflow tank: http://www.ebay.com/itm/NEW-OEM-2002...-/251244652969
Hose just slides on