Re: Non Camaro help needed- Truck overheating
As to the notion that the upper hose felt "under pressure", remember, it can be pressurized from the lower hose thru the radiator, the cooling system is a closed vessel and will pressurize thruout. If the car "is at temp" and you have a cold hose, suspect a bad thermostat.
As was noted above, Chrysler water pump impellers are known to come loose which will manifest as good temp at idle, overheat at speed.
Just went thru all of this with my PT Cruiser and it turned out to be a bad radiator cap, of course, in my case, I was losing coolant. Pressure tested the cap and it failed, new cap=happy wife and car.