99 suburban 5.7 4 wheel dr., 1500. after sitting all night it wants to stumble at first start, like its getting too much gas or not enough. after that its just fine. fuel pump, regulater or injecters?

Cycle the ignition switch once or twice before starting. If it runs fine the pump could be going out. Don't want to leave out the pressure regulator, seen more of the pumps to be the cause of your description.

maybe fuel filter, if its not in the tank

fuel pressure regulator are really bad about having leak and after sitting for awhile will have exteneded crank and will run rough for a few seconds