What code you are using to sumit as PDF? I have not done submittion to ASP page but done to a Servlet earlier.
In that scenario, we were submitting the XML data from the form to Servlet.
If you place the button of type Submit, then you get the option to change it to Submit as PDF (check the Submit tab of the properties).
In the preSubmit event, you can execute the code to submit to your ASP page.
this.resolveNode("#event").submit.target = "PROVIDE URL HERE";
Hope this helps..
Thanks
Srini