It was such an emotional/touching/sentimental movie that I wept uncontrollably while watching it.
Do all of the bolded words fit in the above and convey the same idea? Thanks.

Student or Learner
It was such an emotional/touching/sentimental movie that I wept uncontrollably while watching it.
Do all of the bolded words fit in the above and convey the same idea? Thanks.
The first two do. I'd say "sentimental" had more of a sense of syrupy/over-sweet.
A word you might find useful when talking about this sort of movie is 'tear-jerker'.
"Have you seen Titanic? It's a real tear-jerker. I cried buckets."
[Personal note:I haven't seen it, honest!]
b
And another synonym for "tear-jerker" is "weepie", for obvious reasons - a movie that make you weep.
The word "sentimental" collocates typically with "song/lullaby". A sentimental song makes you feel something [positive - love, for example, rather than hatred]. ("Sentimental" also collocates with "reasons" and "value", but in a different sense: "These cuff-links are worthless, but they have immense sentimental value for me because my father gave them to me" - in this case, the "value" is of a kind that relates to sentiment. In the first case, the song is sentimental.
I wouldn't expect to see the word 'sentimental' attributed to a movie, unless the movie was specifically aimed at arousing emotions in a rather clumsy and perhaps rather obvious way. But other people may feel differently!
b
Not generally. I was just saying that my interpretation of of "sentimental" in that context ['sentimental movie'] would be 'syrupy'.
You're right, 'syrupy' normally has a negative sense, so I wouldn't say 'too syrupy' - which suggests that a certain amount of 'syrupiness' is OK. 'Syrupy' on its own already has the sense of 'too sentimental'.
b