GZ 250 Forums - Keeps cutting off

My best friend owns an 04 gz250, it had been running just fine until yesterday when he went to meet a guy to trade bikes, while he was test ridding the guys 600 shadow the other guys was testing riding he's. Well when he came back the guy was messing with his idle screw(they didn't take yet he's waiting on his title to come in so they can). On his way home at a red light puts it in neutral and he said it boged. I went to me to help him but it seemed like it was flooded. We towed it back to his how and let it sit, today trying to get it started it will crank and only stay on if the throttle is being held, I've adjusted the screw to where it will stay running, but it's reving high. It also seeming when I would release the throttle it would start reving a lot higher and not want to come down. Any idea what could be the issue? Would cleaning the carbs do the trick?

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