If your transmission doesn’t shift out of first gear or shifts hard at too high a R.P.M. this doesn’t always mean you have a problem. This could be a stuck throttle valve caused by a small piece of trash. This sometimes happens after a rebuild. Sometimes the throttle valve can be unstuck without removing the valve body. Get up to about 20 to 30 M.P.H. and hit the gas pedal on and off hard with your foot. This might do the job. If that doesn’t work remove the throttle valve cable end from the throttle, with the motor at idle in park, pull the cable in and out very fast, this might work, if not the valve body must be removed by a transmission shop to be unstuck. This could cost $50.00 to $100.00.