NAC is quite fantastic. Not just for energy, but for autism too, in which glutamate dysfunction is also implicated! Some people do just as well with sulforaphane as well, which I really need to do.
Jarrow has a great NAC extended release brand, I've been spotty with it recently but it feels really good when I take it. Feels like my autism symptoms go down half a notch (i.e. the opposite direction of aspartame, lol), my energy goes up, and I just sorta feel more 'real', for lack of a better word.
Very great medication/molecule, all around, it does so much more than that, too (for example, NAC is just glutathione without the glutamate component IIRC, and that's how it binds the glutamate out of your bloodstream. 2 huge birds, one spicy sulfurey stone). Let's hope it stays open access, for all of the benefits it has.
I don't have any chronic infections that I'm aware of (maybe the athletes foot) but I have experienced a stark enough improvement in overall sense of wellbeing from taking NAC that I sort of characterize my own recent history in to pre-and-post NAC phases. It's a great molecule.