Yeah, there will be an idle adjust screw somewhere on the side of the carb(s). you're looing for a screw that probably has a spring between it's head and the thing it's fixed into (stops it vibratiing out when open throttle), which is hit by the throttle mechanism at "closed" position, but appears to do absolutely nothing when the throttle is opened.
I have tried getting into
but for some reason it won't let me see the pdf this morning. If you manage to download it (or the one for your MY of engine) look for the carb page, and one of the numbers should point to the "idle speed adjuster" or words to that effect.
Probably won't need more than about half a turn. If you can't find it or it doesn't work, post back and hopefully my Acrobat reader wil lhave woken up so I can be a bit more helpful.