What would cause a 1992 Chevy astro with a v 6 4.3l and a throttle body carb on a new engine will not start when it gets cold it has all new elec and timing is set right?

Poor starting when cold indicates choke problems, make sure it is closing when cold and opening as it warms up, to test cover the throttle body with your hand and have someone crank the engine when it normally would have trouble starting and if it starts right up but dies when you remove your hand then that is it, also check fuel delivery such as fuel filter, and spark plug condition.