Won't idle when warm

[PSM]

Hello I have a 2000 gz250 with 15,364 miles that's driving me crazy lol. I've been working on my own bikes for as long as I can remember so I know a bit about fixing these things. Soon as the engine gets warm it won't idle for more then 10-15 seconds. It will idle hi or normal and then just gets slower and slower till it dies. It starts right up but the more it dies the harder it gets to restart. I've cleaned the carb a dozen times at this point and made sure the pilot jet is perfectly clean. So I know that's not the problem and I've sprayed carb cleaner all over the place will engine's running with no results so I know there's no air leaks. I've also check the petcock to make sure it's working right and it is. So what am I missing? I can't think of anything else that would cause this. Usually I clean the carb or replace a leaky hose and it fixes the problem every time know matter what bike i'm working on but this time no such luck. Any help would be greatly appreciated! Thanks!