My '90 GS500 idles (1.2-1.5k) and starts up correctly but after it warms up and I take it down my street to stop at the first light/stop sign, it seems to stay at 3k for 30 seconds or so until it drops down to normal idle range. Just wanted to check with you guys to see what could possibly be causing this. Thanks in advance! Its been driving me crazy!!!

When you say 'after it warms up', how much time are you talking about after starting?  And, do you still have it choked?

I give it around 10 minutes of idling to warm up. The choke is completely off after the 10 minutes (maybe sooner).

Check for vacuum leaks, check the float heights, and synchronize the carbs. Also, make sure the choke cable is fully functional--I just had to replace mine because it was a bit sticky and didn't close the choke entirely.

Could be:
Hanging Idle (leaks near carbs - spray with wd40 to test)
Sticky choke / Throttle cable

10mins on choke?.. I thought 3mins was too much on full choke. Though, my gs does rev to 5k on full choke..

@Ross: I checked float height and sync'd the carbs, so everything should be okay there. Where/how should I check for vacuum leaks?

@Vinny: 10 mins on idle. Choke is less than 10 for sure. How would I test for a hanging idle? Would I see bubbles form with the wd-40, or would it increase rpms?

Sorry guys i'm a bit new at this stuff...

To check for vacuum leaks, spray WD40 around the carb boots and around the tops of the carbs while the engine is running. If the engine revs up, you've found a vacuum leak.