Usually my revisions stall because the demands of family and life absorb my time and creative energy. I think of those as physical stalls. Revisions can also stall for intellectual reasons. Good ideas are replaced by a plague of contrived schemes. Intellectual stalls are something I can control. I start by asking questions.
What is happening? Often the story founders because the characters aren’t doing anything.
Who is there? Have unnecessary characters been introduced on a whim? Are too few characters involved in the scene?
How does this scene push the plot forward?
Why is the scene/subplot/idea essential for the chain reaction of the plot arc?
When the scene unfolds, how will the characters change?