Saving String Data as a file to the SharePoint Server

I am getting a 403 Forbidden access when I try to have my C# web part add a file to the _layout/mapped folder on the SharePoint server.  There must be another way.  The code runs fine in development of course because I have Site Collection Administrator permissions.

The code is wrapped in RunWithElevatedPrivileges but this is where the 403 is coming from. 

I believe the problem lies in the fact that the file needs to be created before it can be

uploaded.  The code turns a string into a file to be uploaded (It is an InfoPath Form in a document library).

The code:

1) takes a row from the .csv file supplied by the user,

2) adds the pertinent fields into a string template of XML code(InfoPath),

3) saves that code in a string array ("res[x]" below),

4) that string is saved via filestream in the _layouts mappedfolder as a

.txt file,

5) and the .txt file is uploaded into the existing SharePoint Document

Library ("SubFolder" below) with an .xml extension ("fileToUpload" below):

 SPSecurity.RunWithElevatedPrivileges(delegate()

              {

                   string myMapPathLayouts =

Page.Server.MapPath("/_layouts/ConvertCSVtoXML_WebPart/");

                           string tempFile = myMapPathLayouts + "/" +  "MyTest" + x + ".txt";

                           using (FileStream fileStream = File.Create(tempFile))

                           {

                               AddText(fileStream, res[x]);

                               SPFile spfile = SubFolder.Files.Add(fileToUpload, fileStream, replaceExistingFiles);

                               SubFolder.Update();

                            }

                 File.Delete(tempFile);

               });

Please help...