I'm not sure temperatures are really that critical. All you are trying to do is dissolve sugars off the grains into the water. The hotter the better.
Yes, too high supposedly extracts tannins, but can you really notice them; it's only a half pound or so in a 5 gallon batch.
I know it is not the best practice (today), but Dave Line (Brewing Beers like those you buy), said to leave the steeping grains in for the whole boil. I'm guessing it didn't make too much difference.
I agree, don't boil the grains, but I see no reason to be anal about what temperature to steep at. I usually partial mash, but when I do steep, I add the grains at the start (cold), add heat to bring the water to a boil, and remove them when the temperature gets to about 170 F.