Hi, i have a honda fit 2002 model with high rpm when driving at a low speed say maybe rpm of 4000 at a speed of 80km/hr. It revs so hard i can always it. It also seem to struggle to shift to the next gear when at a speed of 75-80 because i can see the rpm rev up and down until it engages the next gear after sometime. The problem is it does not show any trouble codes or light. I have tried changing the transmission twice, cleaned the throttle and the fuel tank but no change. Kindly help what could be the problem? Thanks