I have a 402 BBC with a 350 transmission engine is almost stock. But i have a 3000 stall converter that i thought was a regular stall in the car what will happen from having a to big of stall converter on your car because im currently not getting no low end torque and it seems like the car RPMS are running high but not getting a good take off speed.

If stall speed is too high, you may suffer performance-wise. Many street converters get their stall speed from methods that are not condusive to efficiency, like extremely negative fin angles inside the converter. A 402 usually does like a bit of stall speed due to its shorter stroke though. A more mild 402 may prefer a converter under the 3K stall area though if only street-driven.