The official update:
Cory goes down now well at 7:30 and sleeps until 12:30 or 1:30 am. I feed him a bottle and he goes back to sleep until 7am.
I guess the 4-6am thing was a hunger problem. Now with the later feed he can go the distance. I guess it makes sense... if he feeds at 11pm and is not hungry... he doesn't take as much.
Thanks for your help!!!!