I can have emotional outbursts, but I really have to be pushed. It's the final straw when I've been backed into a corner, and then my temper is bad. Almost the only person who inspires these blow ups is my older sister. She's an ESFP and extremely opinionated and incapable of grasping anything abstract (it's always written off as "irrelevant" and "unrelated"), so I do end up tearing my hair out around her because my viewpoint is thoroughly invalidated. Quite honestly, I think she asks for it.
Sometimes I do the Amelie thing and seek secret revenge. That's probably an unhealthy INFP reaction .
I am admittedly temperamental & high-strung too, but the moodiness is subdued. If I do express it, then it's very subtle & passive, through the face or body language. It's so subtle that sometimes people misinterpret my quiet, neutral behavior as "moody", because I'm just not expressive. I'll also internalize negative feelings to the point of it affecting my physical health.
For example, I read once that if you work with an INFP, you likely know very little about them and probably not enough to type them. That sounds about right. We're generally extremely private, and unhealthy ones may become withdrawn to the point of being zombie-like. People at my old job used to joke that I didn't speak for the entire first year I worked there. Funnily enough, I found that job frustrating and stressful because of the stupid clients, yet my co-workers never heard much about it from me, except the odd sarcastic comment here & there. I generally just used wry humor to express my annoyance.