I have had my Escalade for about three months now and for the past three weeks have experienced a cold/rough start issue and was wondering if anyone had any advice to what may be the problem. After the initial start it will start with no issues. It only happens when it has been sitting say overnight or something like that. Thanks for the help in advance.

I would start by checking the fuel pressure with the engine off.
Cycle the key on , watch for the pressure to jump up quickly.
Then monitor the guage to see if the system maintains pressure with the key off.
If pressure drops you have a leak in your fuel system.
The 3 internal leaks would be either the fuel pump check valve, the fuel pressure regulator or one or more injector