wǒ xiǎng qù chāoshì, kěshì méi shíjiān.

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Breakdown of wǒ xiǎng qù chāoshì, kěshì méi shíjiān.

• 没méi: not
• 去qù: to go
• 想xiǎng: to want to

Questions & Answers about wǒ xiǎng qù chāoshì, kěshì méi shíjiān.

What nuance does 想 (xiǎng) convey here compared with 要 (yào), 想要 (xiǎngyào), or 打算 (dǎsuàn)?

• 想 = would like to; a softer, tentative wish or intention.
• 要 = will/going to; stronger, more determined or scheduled intention (can sound firm or even demanding in 1st person).
• 想要 = often interchangeable with 想 before verbs; clearly means “want” before nouns; slightly more emotive.
• 打算 = plan to; emphasizes a plan rather than desire, often with details/time.

Where did the subject go in the second clause? Why is it just 可是没时间 without 我?

Chinese frequently drops subjects when they’re obvious from context. The implied subject is still 我. You could say 可是我没时间 for emphasis or clarity, but leaving out 我 is natural and concise.

Why 没 (méi) and not 不 (bù)? And is 没时间 just shorthand for 没有时间?

Use 没(有) to negate possession/existence and past events: 没(有)时间, 没去. Use 不 for habitual/volitional negation: 不想, 不去.
没时间 = 没有时间; both are correct. 没时间 is a bit more colloquial, but there’s no real difference in meaning here.