Inconsistent Idle

[Narsil]

Hey all! I recently got a 2000 GZ250 Marauder for the Wife to learn on. Had to put a new stator and battery in it. Cleaned the carb (completely stripped 90' soapy water for a few hours, compressed air through all passages including pin-holes, followed by acetone and more compressed air). Repaired a hold in the exhaust, extracted a broken exhaust manifold bolt and replaced them all with stainless bolts.

She's loving it, it's a great bike! But it doesn't idle well. You can set the idle, and it will sit there, and then it will slowly start to die, so you turn up the idle, up and up, and eventually it stabilizes and will seem to be idling well, so you go for a ride, but after running at higher rpm for a while, you come to a stop, and now the idle is way to high. So you lower the idle, down down down, and it idles well, but then if you let it sit for a bit like that, it'll slowly degrade and die. So you idle up up up, and start all over again.

I'm thinking there is a leak somewhere that fluctuates with temperature. I've tried spraying carb cleaner around the carb boots, and couldn't see any sign of it getting sucked in. I tried blowing propane from my torch around the boots as well, and could hear no change in the engine. I'm thinking of taking the top end apart, cleaning valves, replacing seals, maybe rings.

But I'm looking for ideas or suggestions, any ideas? Let me know!