hard starting after warmed up?

[willow72]

i have a 350 vortec crate motor it starts fine in the mornings or after it sits about an hour but if i drive it up to the store and try to run in and out it acts like the battery is about dead i just put a new starter on thinking this would fix the problem but it didnt timing seems to be right the starter i put on is one of those gear reduction high torq starter any help would be great