4L60E 3&4 shifting problem need help

[Mikko82]

I have a 1994 Silverado with 4L60E transmission.   When I take off the truck will shift all the way to 4th gear, but if I slow down and it shifts to 3rd it won't go back to 4th.  Also the same thing happens when I it downshifts from 3rd to 2nd, it won't shift back to 3rd.  If I stay at the correct speed it doesn't downshift on it's own.  So I will pull over and turn the truck off for a few minutes then go again might have to do it a few times until it will go back to 4th.

Changed the shift solenoid but that wasn't it.  Any professional advise is much appreciated!