My 2006 Durango runs hot after a while . It's not losing much coolant. Also if the cap is off and you start it, Iit will blow back water out the opening. I thought it may have a head gasket crack or even a cracked block. Because it had a miss. I put some K&W nanotechnology head gasket and block seal. I followed the instructions except I didn't pull the plugs to check for coolant remnance. I FLUSHED the radiator with water 4 times. (Still running hot and I believe the water pump is pumping)
Head/ Block seal doesn't always work. It's also pretty controversial about what happens when you put it in. I've used it a few times and it only worked once. There is also no real scientific evidence that it works, it's more of "Theoretically" it should work.
That being said, don't automatically assume you have a head leak or block leak. Running hot can also cause misfires. Especially with that truck. Chrysler computers are super finicky.
Blowing water out of the cap, can be normal. This also could be an indication of a thermostat issue or a clogged heater core. The first and easiest thing you could do, Is grab one of those master cooling system testing kits from an auto-store. Make sure everything is sealed up and pressurize the system. See if it holds pressure. If it doesn't hold pressure, then you know you definitely have a leak.
Once you've determined whether or not, you can begin further diagnosis. There is a lack of information here unfortunately, so it's a bit difficult to tell you the proper diagnostic path you should take. You can always come back and update your question so we can edit answers to properly guide you.