I have a full roller 383 motor in my truck with what I think is an Edelbrock Q-Jet style 600cfm carb. If I punch it off the line, it stutters (hic-up) like it isn't getting enough gas, then it takes off fine all the way to 5000rpm. When it shifts you can feel a lag for a split second, but then it starts pulling again. The accelerator pump works fine and the carb is adjusted right, so do I need a larger one? Thanks.