Receiving Connection_Abandoned_By_AppPoo and Connection_Dropped Errors in Web server IIS logs

Hello, we have about 10 web servers fetching data from Flexcube Oracle Database. We are running on Windows 2003 Server Service Pack 2. For the last past weeks we have been experiencing slow performance on the Web pages, sometimes the connection is refused. We drilled down to the iis http error logs and found out that, we had so many errors. Which I have summarized / pasted below.

HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Dropped    DefaultAppPool
HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Dropped    DefaultAppPool
HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Dropped    DefaultAppPool
HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Dropped    DefaultAppPool
HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Dropped    DefaultAppPool

HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Abandoned_By_AppPool    DefaultAppPool
HTTP/1.1    POST    /flexbranch/FormRequest.asp    -    1    Connection_Abandoned_By_AppPool    DefaultAppPool
HTTP/1.1    POST    /flexbranch/TPValidatorService.asp    -    1    Connection_Abandoned_By_AppPool    DefaultAppPool
HTTP/1.1    POST    /flexbranch/conn.asp?statflg=what    -    1    Connection_Abandoned_By_AppPool    DefaultAppPool.

Getting HTTP error code 503 too.

I have researched the internet and saw some articles on the asp crashes. I need some information on how to troubleshoot these errors, since web transactions from client systems never complete due to this connection issue. 

Thank you.