High Idle Speed
I have an '03 Strom & have been experiencing the same problem since shortly after I got the bike. It would randomly remain at approx 3100-3300 rpm when the throttle was closed. I would blip the throttle 2-3-4 times & then the speed would drop. I took it to my local dealer & they replaced/exchanged a number of the sensors on the bike & the problem continued. Some days it worked perfectly & the next day 3-4 traffic lights in a row the speed would remain high. The dealer contacted Suzuki & after a few calls they were able to talk to someone who was familiar w/ this condition. Suzuki indicated a TBS sync at 2500 rpm vs the normal speed seemed to help. This was done on my bike, but the problem remains, however the bike runs much better at slower rpm's, ie less than 4000 - huge improvement.
While riding the bike, I noticed that if I shifted the gearbox up or down when the revs were high, they would immediately drop to the normal idle speed. This works everytime - it's not a cure but is easier than blipping the throttle. Try shifting the gearbox the next time this happens & let me know if the speed drops. If it does work, I would like to send Suzuki a letter outlining this condition, because I consider it to be a potential safety hazard.
Hope this helps,