2009 cts v 6 #4 cylinder miss fire under load
 

I have a miss fire just under load number 4 cylinder 3.6 di replaced coil and plug fuel pressure good

Compression test. Is injector getting pulse? there is no easy way to check if injector is spraying. you could disconnect the other 5 crank engine and see in fuel pressure drops.

Compression good engine will rev up okay after like 2000 rpm no problem