[Jaken54]

First post I have a 2008 bmw N54 with 240,000km I've been getting random misfires the car has catless downpipes, cold air intakes, and 4inch straight pipe right out to the back, I've done Bosch one step colder spark plugs put new coil packs swapped the injectors with different injectors, and still am getting a bad misfire with cold start a loud whistling sound until the car warms up, it has mhd stage 2 I tried reflashing it to stock but fixed nothing, I have data logs that I can post if needed I just want the issue fixed so I can enjoy the car any help or advice would be great!