I love beginnings, I rarely get to endings. What happens in the middle is hard to pace for me. Might be easier if I followed the Hero's journey or other meta-narratives, but I like to write character first. So the middle of the story is where I want to put the characters out in the world and see how they do, what they do, without a conscience reference to the main plot. So for me, when I get to the middle of writing a story it can really meander.
How about yourselves?
Yeah I love short stories because you're basically racing to the end, but I really wanna do novels. I get what you mean about finding the flow. I generally go too long, too wordy and will hopefully trim that down in editing.