I have to face one problem from 7/8 days...
in Transmisasion 4L80E We overhaul it...
now the problem in 4rth Grear

I have this Transmission in GMC Truck 454 Engin Model 1990.

Shifting is OK.. But
When It became in 4rth Gear and I press the full accelator the care take the kick down and become in 3rd... then its runing in 3rd.. never became 4rth until you stop the car. and switch off the Car..

Can you please help me for this..