I am using the fantasysports tables using OAuth, and getting 999 - errors after even 600 requests. It looks like I'm running into the per second rate limit, but I only send at most 3 requests per second. As the rate limit was recently raised to 20,000 requests / hour, I should be able to make 5.4 requests / second. Or, is fantasysports still under the 10,000 / hour limit?
Update: I have also tried staying under 2 requests per second (at 10,000 requests/sec the rate should be 2.77req/sec), but no luck. My requests are actually not returning any results now, so it's not strictly a 999, but a <result/>.