I bought my automatic 93 sentra used. It has 111k miles. Left side of the car is lower than right side. The lining of the frame is off slightly. There is a problem with the left side of the vehicle. After I accelerate to 10mph, I feel a push from under the car to go to second gear. It goes higher and continues to rise normally. I want to know what could cause this "push" after 1st gear? It can be described as the gear shift from 1st to 2nd on a manual car. I don't think this is normal for a car. Are there any ideas of what can be the problem? Will it be simple to fix? How much would it possible cost me? I don't want to take it for a diagnostic ($60) if I don't have to. Some say it needs a new transmission filter. I'm not sure because I don't know about cars. Any help is appreciated.