I recently picked up a 2000 R1 off of Ebay with 2100 miles on it, it had been sitting for a while and some rust in the tank. I rode it home anyway (600 miles), no problem, ran great. I took the gas tank off and chemically removed the rust with the Yamaha rust remover system, put a new fuel filter on it, started it up and now it won't idle after it warms up and the choke is turned off. It will idle at 1000 then gradually goes lower and lower until it stalls out. It runs ok if I keep the throttle opened but it does backfire like crazy when I decelerate in gear. I'm sure nothing got past the fuel filter since I put a new one on before I started it up, so the carbs should be ok. Any ideas?