So I am at a loss. Bought an 04 yz250 2s last April in like new condition. Everything was great. Started doing coal hills, and dropping the bike frequently. During the first season, I noticed a slight stumble in 5th gear while at wot. Over the winter, I tore the bike down, rebuilt the top end with all yamaha parts, put in an n3ew needle set on 2nd position from bottom, and changed air screw setting to 2 turns. Adjusted idle, and bike ran like a raped ape! Couldn't have asked for anything more, and the top end stumble was gone. 2nd ride this year, I flipped the bike on a hill and the forks took a wicked shot on a huge boulder. I immediately noticed the top end lack of power and stumble had returned, only worse than before. Now I noticed it in 4th slightly and 5th bad, and got worse the longer it was at wot. Low end was still great so I continued to ride. The bike sat for 3 months until I fixed the forks, started up fine as well. But when riding it has the same issue, only way worse. I notice it in almost every gear now, and would have what felt like a Rev limiter at half throttle as powerband hit, and will not accelerate. If I roll onto the throttle easy in first and second it will Rev out a little farther but not much. Thinking maybe the race gas went bad from sitting and is making the problem worse? The only thing I can imagine caused this was the impact on the forks felt through the entire bike, or the fact it was upside down for about 10 seconds and running. I have checked tps resistance and is ok. Fuel shutoff sol. LOOKS ok but was not tested. Raised needle clip 1 spot to the middle, turned air screw in to 1 or 1.5. Helped a tad, but not much. Seems if I let it idle for a minute it will Rev out better, almost like a lack of fuel somewhere. Good flow frI'm tank, cleaned carb, air filter clean, checked all elec. Connections. Runs the same with both plugs from carb disconnected. Did I possible damage the powervalve and the bad fuel is making it worse? Seems to foul plugs almost imediately. And I shut off the petcock and bike revs fine in neutral but didn't not ride it like this. That tells me it is rich? At wot, it feels as though it is leaning out and not firing every stroke. Can somebody please help me make sense of this jumble of info? If the pv was stuck closed, at wot it would feed the engine more fuel than its capable of burning while having the flow restricted, I think? Even in 2nd and sometimes 1st, if I go wot to fast it sputters and won't Rev out almost imediately. I'm going to start with fresh fuel and plug, but I know the real issue will still remain. Please help!