S60 has start difficulties or stutters short

Hello to all Volvo drivers, I recently bought a S60 2.4L BJ. 2001. I’m actually completely satisfied with the Volvo. But I’ve been having a small start problem for a few weeks now. Vlt. knows someone the problem and someone can help me from you. If the car has stood for at least 10 hours and I then start the engine and the speed commutes up and then goes very far down. Sometimes the car goes out, he catches himself again. When I give gas stutter After 20sec. everything is fine and the car is running. I can’t detect any logic when the stuttering occurs. AIt has already occurred when it was still warm, in the underground garage, outside when it is cold (-15°C), when it is dry or when it is raining. But as I said, not always. Sometimes there is no more than 2 weeks. I have been looking for the forum and actually only found a throttle problem. If I have a problem with the throttles, I have a problem. This is permanent and not only at the start. Does anyone have a clue and can help me further? Thank you for your efforts…… Michael