Recovering Headers and Request sent from IIS or directly from the browser

I’m currently experiencing errors on particular pages, when an IIS web.config header for Cache Control is added. I have narrowed down the possible root causes, to me the following is the most likely: The headers and/or request headers are different; I need to recover those headers and request data sent from IIS or directly from the browser.

in the Application.cfc, I prepended the following to a function named “OnRequest”

I have tried getPageContext().getRequest().getHeaderNames(), but it errors on the last call
I have tried getHTTPRequestData() it returns nothing

Are there any other suggestions for how I can get the forwarded request headers from IIS or the browser?