I recently bought a 2002 Polaris Pro X 440 Fan. 2k miles on frame with a fresh rebuild from previous owner. The rebuild was done professionally. I was in change of breaking in the engine, I mixed oil into the gas tank (16 oz/1 pint) to 5 gallons. It ran fine like that until... well until it didnt. It started to bog down and then eventually died and wouldnt start. Took the spark plugs out and I was amazed it was still running, super fouled. Replaced them and rode on. Well now I can hardly take off. The clutch engages at 4500 rpms. The engine cant seem to push past that without me getting off and pushing it. Once I hit 5500 rpms it runs great! I put seafoam in the tank (16oz to 10.5 gallons) and that helped a little. But its still boggy on take off, but will start with me on it (only on flat ground tho, and very slowly) cant even pull its self up a hill from a stop. Newish primary spring so I'm not worried about that. OEM belt,91 ethanol free gas. It ran good for 20-30 miles after I got it. I've put about 180 miles on since i got it and its not clearing up, at least not yet. any advice?