This is copied from your other post in General Beer Discussions
Both those methods are accepted standards fro steeping grains. As long as the water doesn't get too much above 160F, and even then if you're not leaving them in at that temperature for more than a couple of minutes, you should be okay. The "leftover little bits" should not cause an off flavor unless your steeping bag broke and you end up boiling half the contents.
Can you describe your off flavor and the rest of your process? Including things like your sanitation routine?