Qashqai starts with difficulty and has no engine power

Hello,

History: The engine was replaced in April 2023 following a breakdown (new refurbished engine, 60,000 km). The DPF was cleaned when the new engine was installed.

Since then, the car has been running without problems, except until the end of December 2023, when a problem with the clutch pedal required the replacement of both the clutch master and slave cylinders.

I got the car back, but since then, it has been very difficult to start the engine and lacks power (unable to climb a hill but no black smoke) + there is the check engine light on. The mechanic who replaced the clutch and the first engine decided to replace the injectors with the old ones from the first engine; this did not make any difference.

Do you have any idea what could be causing my breakdown? The car was running perfectly before the clutch master and slave cylinders were replaced. Could it be related to this intervention?

Thank you in advance to those who will take the time to look into my problem.

Simon