When the problem first started the shop I took it too pressure tested, and found a leak on one of the hoses. When they replaced the hoses, the problem went away for a few weeks. When the problem came back, though not as bad as the first time, they pressure tested it again. That's when they replaced the radiator. If there was a gasket problem, wouldn't they have found it then? I ran it for over 4 hours today, the gauge only got up to the midway mark at it's hottest. And it is 100 here today, so it's really hot. I'm starting to think it's the coolant not being 50/50 antifreeze and water. Or maybe some air in the line somewhere.

 

Where do you live? When I lived in Arizona I never ran 50/50 I always ran more water then antifreeze, at least 60% water if not more. Cooling systems aren't that complicated, it's not like an electrical system where you have a broken wire somewhere between the front and rear of the truck. Or a leak you can't quite track down that drips on the back of the motor. Is this a trusted shop you keep bringing the truck too? I've had to refix countless things for friends that shops did and screwed up. Last year I replaced a head gasket (And did the water pump while the car was apart) on an 06 civic that was diagnosed with a bad radiator and it was actually the head gasket. I also had to replace the radiator because they put the wrong radiator in.

 

Live in Oklahoma. It's a trusted shop around here, I've not had any problems with them before.