Moin, I’ve been driving a Blackbird Bj 99 , 150 PSD for 5 years. For a few months the engine spins after the start with about 3500 rpm. And it takes almost 3 minutes until it goes down to 1500 and another 10 min. to get to 1100. Earlier after the start so to 1800 rpm. And so after 40 sec. On 1100. I asked already at the workshop and as an answer only one: “This can be due to everything possible and I can drive with it without danger. But it sucks totally and costs quite nice fuel. such a problem had before or maybe knows what it is? For ideas I would be very grateful. Greeting Thomas