first gear cuts out hard when throttle hammered at low rpm

my 97 cobra cut out once in first, once in second gear at low speed and rpm. the cutout is hard. the third cutout was in first gear again and resulted in a stall. car would not start. changed fuel pump and fuse. runs fine all the time unless I hammer again in first. Third, fourth and fifth are all fine under heavy load,havent tried hammering it in second at low speed. also reving the car in idle responds fine all the time. I do have a four bank chip in it. there is literally no miss at any point, just a hard cutout at basically standstill and heavy load in first?i can come out of first and wind the rpms under steady gas with no problem. just cant floor it at once out of the hole.thanks for any help