Is There A Limit On The Size Of A Http Argument Value In A HttpWebRequest

I am testing out a few different public RESTful APIs each differing in http argument value name, but in concept all work similarly. However none of the companies are connected so it must be something on my end.

Within .NET I get the following error when trying to obtain the HttpWebResponse:
Message: "The server committed a protocol violation. Section=ResponseStatusLine"
Status: ServerProtocolViolation {11}
Using Fiddler, I am finding that the headers coming back are non-existent and this is the cause of the issue (not even present and improperly formatted):
HTTP/1.0 200 This buggy server did not return headers
The parameter I am sending in is a lengthy text news article. I have stripped ALL puntuation, characters, etc just to make sure nothing wans interferring. I build the text out using a StringBuilder and then create the URI like below:
Dim sb As New StringBuilder
sb.Append("&apiKey=" + HttpUtility.UrlEncode("123456789"))
sb.Append("&inputText=" + HttpUtility.UrlEncode(Me.MyTestText))
Dim ApiHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(New Uri(BaseRequestURL + sb.ToString.Trim())), HttpWebRequest)
Dim ApiHttpWebResponse As HttpWebResponse = CType(ApiHttpWebRequest.GetResponse(), HttpWebResponse)

This code DOES work with most text I send it. The interesting thing I am finding is that if I shorten the text I am sending then it works! I can't figure out exactly the threashold or breaking point. The stringbuilders values expand after the HttpUtility.UrlEncode function is run against it. However the text in size is only about 5-8 kilobytes in size and well below any size limitations set forth by the 'httpWebRequest' .config settings as laid out in the MSDN or by that of any of the APIs I am using (for example 1 limit is 150 kilobytes of text). I even tried setting all of those values to "-1" in the web.config which means: "A value of -1 indicates that no size limit will be imposed on the response headers."