It shifts from 1st gear to 3rd gear fine but not to 4th gear. If you inclined down the road or even on a level road with 45 MPH and about 2500 RPM as soon as you remove your foot from gas pedal you feel the car freely continue to go and the engine RPM goes to idle and there is no engine breaking causing the car to slow down. As soon as you press the gas pedal again and increase the RPM to whatever it was before, it'll continue to accelerate and move forward in 3rd gear. Any idea why it's doing this?