Default app pool does not support more connection of text driver after some time

Default app pool does not support more connection of text driver after some time but if we reset iis then it working fine (we are closing and disposing connection as well) this problem comes after every 4 to 5 hours and it also depends on site load all page except text driver connection or oledb connection page works fine

and if we test with some other app pool when at hanging time it also works fine for different app pool and all the page works fine with text driver page etc..