My 2003 Chevy Venture loses power while driving, the hot coolant light comes on and the temperature gauge goes all the way to the red mark. There is coolant in the radiator and in the reservior and the engine oil doesn't show any signs of coolant. Just had a oil change a few days ago. Had the radiator flushed a few months ago, the transmission flushed, fuel filter replaced, new plug wires, all within the last 5 months.
Check the thermostat and water pump. Remove the thermostat and see if that corrects the problem. If not, replace the water pump. It's a good idea to replace the thermostat when replacing the water pump, but not 100% must do.