I don't think I'm bothered if people's words tumble out willy nilly...mine do that sometimes! It's really the "sounding very definitive while still just tossing round ideas" thing that gets me - like, about life decisions, commitments involving others, etc. And I think it's very much an extrovert thing too.
I probably sound even more rigid on this than I am. It is seldom that I would call someone out on it, for instance. Unfortunately, if I DO get to the point of calling someone out, I've probably reached a massive level of frustration over the whole issue and it has actually occurred many times.
I appreciate what you've said about steps you've made to modify your communication style. And honestly, this is something everyone should be prepared to do. If it bothers me that much, instead of just getting massively frustrated, I should look at finding different ways to explore topics, or just not take everything they say as gospel just because that happens to be more my communication style...etc. Types and just PEOPLE have to meet each other halfway.
I think that just saying "I'm thinking about this" instead of "I am about to do this, it is a done deal" can make a big difference. I mean, who am I kidding? I'm an anxious Ni-driven type 6! If I'm with someone who doesn't mind me venting/thinking aloud, I can throw around possibilities about courses of action, about why others do the things they do, etc etc all day long. But the only (few) times in my life when I can remember saying "I AM DOING THIS. IT IS A DONE DEAL" and then I didn't do it...I was in a state of high emotional turmoil and wanted to find some resolution though my feelings hadn't settled down. So in my case it was yet another indicator that it's a good idea for feelings to settle down before you make those definitive statements - or take definitive actions, as well.
I hear what you say too about feeling rejected if you're sharing "unfiltered emotion." I do think everyone should be able to do that without being judged or tuned out. With one or two people I know well, like my probable ENFP friend, there have been problems in the past over her making definite statements and then me feeling let down. At least one situation arose around this where I felt I'd been lied to, or at least she was less than honest and a bit manipulative, and that obviously caused strain. However, I have a better idea now because I know her quite well (though I still can't always be sure) of when she is venting/feeling something in the moment that will change, and when it is a more long-term conviction or decision.
However, I wouldn't have thought ENTPs would be so bothered by this sort of thing? Would they not be more like ENFPs in that respect? It would surprise me if the same things bothered ENTPs and INFJs in regard to communication styles, etc. Maybe this is just your ENTP?