I've changed my dynamic pages (page.php?id=***) to /page/subject.html with this .htaccess script: > forcetype application/x-httpd-php
But, I often see very untargeted ads, that are related to other pages. E.g. I've got a page about cars and a page about books. The cars-page is more popular, but also on the books-page and even the cats-page Adsense is showing Cars-ads. But, the word Car is not on the page.
So I doubt if the forcetype script is working very well with Adsense. Should I use modrewrite? Will that work better? And why?
The rewriting etc. happening server-side is irrelevant - it is the end result that matters. Assuming that calling /page/subject.html shows the correct page with a 200 OK code, then everything is working correctly. Your targeting problems will be coming from elsewhere, maybe to do with the fact that you recently changed all of your page names.