96 Impala SS 4L60E problems
Transmission doesn't like to shift into 4th gear until 50 mph sometimes.
Sometimes it will shift into 4th gear at 40 mph and then has a 500 rpm surge until it either shifts back into 3rd or it archives 50-55mph and then the torque converter locks up.
I can manually shift the car into 4th gear with my scan tool, and it operates fine.
Kinda baffled here.....

