a4ld shift problem

[2wdmuddin]

i was searhing on line to try and figure out what could be wrong with my truck and i found this information (A4LD
This transmission is a rear wheel drive 4 speed automatic. Common symptoms are erratic shifting, hesitating going into gear and losing transmission fluid without a trace of a leak. You have a modulator on the passenger's side of the vehicle pointing towards the driver's door. Pull the rubber line off the modulator and see it trans fluid comes out of the line. Now, if it does your modulator is no good. It can cause any of the above symptoms. If the vehicle speed sensor goes bad it can cause a no 4th gear symptom.)
could this be the rason my truck shifts back and forth between 3rd and 4th at random? if not does anyone know what i can do?

 

[JustME]

Sounds like my trans as well. I found it is really temperamental as far a fluid is concerned. A bit to much and she slams through the gears and just a little low and lots of hesitation. I will have to check both the modulator and speed sensor. Thanks