Stop receiving search feeds after some time in Application only mode


I was able to make 450 search request for first 15 minutes and was getting proper response from rest API. But after 15-20 minutes later response suddenly stops from twitter API. I have seen my request count decreasing per every request but no response from twitter. I also verified using browser and they are not at all in sync.

Do REST API slowing down the the rate at which application-only user receives feed after some time? Please help.