2010 X5 xdrive 35d motor shutting down

[Shriff]

Hi, my 35d just stopped on highway without warning. No warning lights illuminated. Try to restart and no go. Switch key off and back on and it starts first go and sounds perfect. Quietly move off and motor is fine. However, if you accelerate hard the motor will cut out. Interestingly, when the motor is cold it Purrs under any type of acceleration. Simply, when cold no problems.
I have read re broken partition and the flooding of injector 5. Yes my plastic partition is broken.
Also on a scan it said DDE activation cylinder 5 injector.
I plan to access injector asap however was wondering why there is no problem when cold. If anyone has any thoughts your help would be appreciated.

Kind Regards