Generating Long JSON Format Text Using API: Seeking Improvements

Hi there!
I’m trying to generate a long JSON format text using ChatGPT-4o, but it repeatedly returns incomplete JSON with '''json and ''' . Additionally, the JSON format is often not completed, sometimes lacking curly brackets and commas. The process I’m using involves extracting text from Word files, then passing that text to the API and asking it to convert the text into JSON format.
Since the text is quite long, I’m passing it to the API in segments and then combining the responses into a single file as I receive them. After I receive all the segments, I convert the file into JSON format with another code. Is there a better way to convert long text into JSON format?

Also, with ChatGPT-3.5-turbo, I can get better answers than with ChatGPT-4o. I’m not sure why

Is it too long?

 model="gpt-4o",
        messages=[
            {"role": "system", "content": "You are a survey generator."},
            {
                "role": "user",
                "content": f"""
Convert the following text into a JSON format for a survey with the following structure:

{{
    "question_number": "<number>",
    "question_text": "<question_content>",
    "response_type": "<single_text|single_slide|multi_text|free_text_single|free_text_multi>",
    "options": [
        {{
            "option_number": "<number>",
            "option_text": "<text>"
        }}
    ],
    "others": "<other information>"
}}

Here is the text to convert:

{chunk}

Ensure the format is correct, paying attention to curly brackets and commas.
"""
                }