Turning off "Searchid" in vbulletin
 

I am using a recently unsupported hack for vbulletin Called Extra Threadfields. Everything works great aside from this one search bug.

http://www.onereef.com/forums/search.php

To create the bug do this:

1. Check a box under "Search Predefined Keywords" (do not enter any text into the keyword field)
2. Execute a search and note the searchid in the url
3. Go back to the search page, select a different box or more boxes
4. Execute another search and note that the searchid in the url is the same.

My question is, how does one turn off the option to call the searchid. Or how can I clear out the searchid cache more frequently?