Roller accelerates very badly

Hello So I still have the problem my scooter (Flex tech fun 50) Accelerates very slowly before he did very well Accelerated and pulled and doesn’t jrtzt nothing So I did gassing 1 month ago or so sport Auspuff and everything was good a few weeks later he ran like I described So with the exhaust were still clutch springs but I haven’t yet installed I also bought a new intake nozzle and sports air filter it hasn’t changed anything K Can you help me????