RPM's not dropping

[grayghost]

1st time this has happened- rode today and when i pulled up to the house, letting off the throttle, the RPMs didn't drop down, but the throttle itself did not seem to be sticking. checked the choke (was off) and lubed throttle cable. doesn't do it all the time, but after highway speeds (55-70 mph) seems most apt to.
any ideas?

[theUBS]

Are your trips on the highway your only longer trips?  If so, maybe those are the only times you really ever reach FULL operating temps.  I'd try just adjusting the idle down a bit first.

http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/AdjustIdle

[fred]

1st time this has happened- rode today and when i pulled up to the house, letting off the throttle, the RPMs didn't drop down, but the throttle itself did not seem to be sticking. checked the choke (was off) and lubed throttle cable. doesn't do it all the time, but after highway speeds (55-70 mph) seems most apt to.
any ideas?

You have a vacuum leak most likely. Search for vacuum leak and idle hang on the forum and you should be able to find detailed instructions on how to diagnose and fix your problem. If I had to take a wild guess, I'd have to go with cracked intake boots. Those things get pretty brittle after a while.