Drago, you're not alone. Special operators harvest slow as hell and burn out your proxies fast. G is far more restrictive on special operators than on regular queries. I was once doing keyword research and needed to enter around 100 allintitle: queries over the space of an hour. I thought it wouldn't be a problem. I was wrong - I was IP banned after around 50 queries. Even if you have hundreds or thousands of proxies, unfortunately they will burn out too quickly. At all costs, I avoid scraping using special operators. With any substantial lists, it's practically impossible to do. I harvest tens or even hundreds of millions of URLs at a time - this would be impossible with special operators. A few thousand URLs would be alright, but once you're pushing past a million assuming you get there as it's so damn slow, you are screwed.
My 'solution' to this is just a simple workaround. Instead of using the inurl: operator, use the string in quotes. For example, rather than inurl:index.php? you will be doing "index.php?" . You will often find that you get just as targeted results as with the inurl operator, i.e. accurate / the URLs you are looking for. But just to check, go into your browser and google the string in quotes and take a look at the URLs that come up. Click on a few and browse them. Are they still what you are looking for? If so, then great.
Often, if the inurl: string is quite unique, then simply putting it in quotation marks suffices, because G searches not only the page content, but also the url content, in fact, url content is one of the main things determining search results, ask any owner of an exact match domain. Putting "sadasdfasnh43???php_content=op&At3232" instead of inurl:sadasdfasnh43???php_content=op&At3232 is hardly going to lead to much difference, because the string is so unique G will have to find it in the URL, not the page text itself. Try it out.