I have a 01 Dodge Ram 1500 with a 3.9L V6 and it overheats. I replaced the radiator, thermostat and water pump and it still overheats. I borrowed a block checker and to check for Co2 gasses in the coolant. It checked good. It will not overheat at idle unless the A/C is on. I moved the temp switch from hot to cold and back several times. My scanner reads no hotter that 196 degrees but if I rev it to 2000 RPM the temp drops to 188. When I drive it then it overheats. Now what?