Temperature rises when I accelerate.

[emaxxster]

When I have to accelerate to get onto the highway, or the van down shifts to maintain a speed up a hill while I have the cruise control on the temperature rises. Even on a open road cruising at 40 mph I will give it enough gas to make it down shift, run it up to 50 and get off the gas and let it start coasting back down to 40 by the time it get back down to 40 the temperature and climbed to one mark over halfway. When I get on level ground again the temperature will come back down to where it normally is, one mark under half. I have just replaced the radiator, my mechanic friend told me that sediment will fill up the lower part of the radiator. That didn’t fix the problem and I could not get coolant out the bleeder by the water pump.