Audi RS4 2015 cold start misfire cylinder 4 and 8

Hi im Julie, I'm new to this site, I wonder if anyone can help, my Audi RS4 has a terrible misfire on cold start up and perfect once it reaches around 90 degrees, its been in the main dealers for the last 6 weeks, they have replaced the plugs, swapped coil packs around, replaced a vacuum pipe, new injectors on cylinder 4 and 8 and apparently cleaned decked the head, they have now given up on it and said engine needs to come out for inspection, this can't be right can it, they have done compression tests, 11 bar on 1-7 and 10.8 bar on cylinder 8.
Has anyone else had this problem
thanks

Hi thanks for that, do you mean a new air filter? How can the MAF be tested, it doesn't show any faults on vagcom for MAF, how can the position be adjusted or set