I've always found that anywhere between about 375 F - 400 F works best for when I'm making muffins. If I'm using only eggwhites, for some reason I need to keep it at a lower temperature otherwise they do burn. (Or if not burn, get that "dried out" kinda texture.)
Do you have a convection oven? We don't have one, and there is a difference... I have had to pre heat the oven for a little longer at 400 F, then just before putting in the muffins, I reduce the heat to 375 F, and that's seemed to solve the burning/overdone dried out texture for me.
Our oven has a pre heat timer, so I'll pre heat it according to that, but then add another 5 minutes onto the pre heat time.
~You don't need to go to culinary school to learn how to cook!~