Multiple httpwebrequest concurrently

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C#

ASP.NET

.NET

When i request Api more then one time, Httpwebrequest or page timeout request Failure takes.If i run script in local no issues take place But in Live Server Timeout issues happens in more than one request. (our live server works in ISS 7, weather the Issue take due this)

below is the code i'm using

for (int i = this.cartDetail.Count - 1; i >= 0; i--)
               {
                   //// Call api submit order using multiple thread
                   this.threads[i] = new Thread(new ThreadStart(this.APISubmitOrder));
                   this.threads[i].Start();
                   this.threads[i].Name = i.ToString(new AcctNumberFormat());
                   this.threads[i].CurrentCulture = CultureInfo.CurrentCulture;
                   this.threads[i].CurrentUICulture = CultureInfo.CurrentUICulture;
               }
               for (int i = this.cartDetail.Count - 1; i >= 0; i--)
               {
                   //// join all thread
                   this.threads[i].Join();
               }

       private void APISubmitOrder()
       {
           ........
             myHttpWebRequest = (HttpWebRequest)WebRequest.Create(strAPIURL);
             //// Encode the Post Data
             byte[] data = ASCIIEncoding.UTF8.GetBytes(strPostData.ToString());
             myHttpWebRequest.Method = "POST";
             myHttpWebRequest.ContentType = "application/x-www-form-urlencoded";
             myHttpWebRequest.ContentLength = data.Length;
             myHttpWebRequest.KeepAlive = false;
             myHttpWebRequest.Timeout = 110000;
             strmrdRequest = myHttpWebRequest.GetRequestStream();
            ////Send the Data
            strmrdRequest.Write(data, 0, data.Length);
            //// Get the http response
            myHttpResponse = myHttpWebRequest.GetResponse();
            //// Get response stream
            strReadResponse = new StreamReader(myHttpResponse.GetResponseStream());
           //// parse response
           string strReadResponseContent = strReadResponse.ReadToEnd();
           .........
       }
       in webconfig
        <httpRuntime maxRequestLength="1024" enable="true" executionTimeout="50000" />

Any help would be appreciated. If you need any more information or a more clear explanation, please do not hesitate to ask.
Thanks!