2001 Focus fuel problem

2001 ford focus, 100,000 miles runs fine until you get low on gas, once I remove the gas cap fill it up with gas, and then it will not idle. I have to drive with 2 feet , one on gas and the other on brake to keep the RPMs up, after I get home and let the car sit for awhile it seems to be fine, until the next time I get low on gas and remove the gas cap. There are no codes that show up on the OBD2, and no check engine light. this has been going on for about 2 months. The fuel pump was replaced by ford about 2 years ago. Any ideas. Thanks ahead of time.