I've been having the same issue—I had a keyboard command set up to bring up Google. I wound up creating an "Open Google" script, and creating the trigger "Open Google | Run"
The script is dead simple: -- tell application "Safari" -- you can replace this with Firefox, of course open location "http://google.com/"; activate -- this brings it to the foreground end tell -- I am sure there is a clever way to pass an argument from QS into the script, which would use the argument as the search key. If that were saved as an action, it would let you do something like "[type random text] | find on google". But I haven't gotten that far.
