Bad shift module?

[Terry]

My truck has been in need of love and care for a while. I am starting to go thru and fix everything before I do any modifications to it. Its a 2.9 86 ext with an A4LD. I have had pretty good luck with it but something in the drive line as not working correctly. I just rebuilt the drive shaft complete with the carrier bearing. The truck has a mind of its own. When I drive it it has a miss like its running out of gas but keeps running. It looses power then runs good and does this unless I put my foot in it then it stops. It tries to downshift when the engine drops off as well. What are the symptoms of a module going bad?

 

[Terry]

Was my question confusing? I will find and fix this but it would be nice if someone could point me to the direction that I need to go.