I am no expert but on Mercedes AMG Engines camshaft sensors and crank position sensors can cause such issues or if you have high mileage might be related to cam chain wear / cam chain tensioner issues.
Hi ive already replaced the camshaft sensors and crank position sensors with not luck :(
I though might have something to do with the pressure but don't know what it meant to be to start with
Okay what sort of mileage has the engine covered ?
If there are some BMW Technicians on here they might know what the fuel rail pressures etc should be. I am new to BMW ownership and have a Petrol variant but a lot of diesels have a low pressure and a high pressure pump. When the engine is hot the High Pressure value can fall due to age and this can cause terrible hot start with the engine cranking for ages before they start again. Just my thoughts you need some expert advice methinks.