I need an urgent Powershell script search site for matching html string

I need a powershell script that a user can run that uses the [login to view URL] file as and input alongside a string. It simply needs to visit each webspage in the sitemap file and search the raw html for a match with the string value. If it finds a match it needs to add that webpage url to a log file output. For example "<h2></h2>" might be the string to find on each page... It needs to log the url and the number of times it found the match. Simple. It will be iterating through a site of ~1800 pages. I'll run it many times to find know issues across the site, to find which pages need fixing. I need this today/tomorrow..