I always run a thermostat with an electric water pump. I don't believe in the "too slow" or "too fast" theories of water flow through an engine, unless they are really, REALLY slow.
I think he has a basic thermodynamics problem. At idle, the engine is putting out less heat, and his electric fans and radiator can keep the coolant cool. Running down the road, the engine is putting out more heat, and the radiator/fan package is not able to keep up, so the coolant temperature is rising. Plugged radiator? Too many things in front of the radiator, blocking it? If it was all new I'd say his radiator is not big enough or the intercooler and trans cooler are blocking too much air, but if he ran the package successfully before, then something has changed...