E70 misfire on cylinder 1

[Markyboyslm]

Just got an E70 4.8. First BMW love it but.... I have an engine light that comes on after it sits overnight. "Cylander 1 misfire" the car stumbles and runs rough. After 1-2 minutes I shut the car off and turn it back on and it runs fine.
I have taken the coil and the spark plug and switched them over to cylinder 5 and still get a code for "cylander 1 misfire"
What should I try next? Could it be my fuel injector? Why would it fail on cold start only? I read maybe the injector could be leaking gas into the engine and cause a misfire on startup. It does start up right away and doesnt crank over too much before starting. No black smoke out the tailpipe either. Plug looked clean.

Not sure if I should just change one injector? Can I get the fuel rail off the others enough just to change the cylander 1 injector without pulling the other injectors out? I would probably need the top gaskets for the others on that side.

Any advice would be appreciated.
Thanks
Marcus