I have been searching for a specific film for around 20 years

Hi everyone

I’ve been searching for a specific film for around 20 years and I’m hoping someone here can help me identify it. Here are the details I remember:

• The film is from the 1970s, possibly early 1980s.

• The setting is in a city, possibly New York.

• The plot involves a group of friends who play a practical joke on a woman, making her believe she is going insane.

• At the beginning of the film, the woman is walking through a park where she sees a man playing percussion (I think he is blind).

• A gunshot is heard, and the woman sees a man in a plaid jacket get shot. When the police arrive, the body is gone, and no one believes her.

• Later, she sees the plaid jacket hanging on a hook in her bathroom. She calls the police again, but the jacket is gone when they arrive.

I’ve been trying to find this film for years with no success. Any help or suggestions on what this film could be would be greatly appreciated!

Thank you in advance!