URL fails to load after x amount of geocodes

Hey guys, I have been using the placefinder api with a PHP script to geocode a few address in my DB for the past two months or so. Previously, it would go through the 50,000 address limit without any issues. (I have a limit hard coded into the PHP to prevent going beyond their limit). However, it recently started failing after anywhere from 20 address, to 3,000 addresses. I haven't made any changes to my code, so I can't understand where this error is coming from. The error specifically is "simplexml request failed to load - URL not loading" or something to that effect. My delay per address is set to 10ms. When it was running fine, it ran without any delay; when it started acting like this, I implemented a 0.1ms and then a 1ms delay. None of the above mentioned delays work. Anyone else experience this?