Hey, hopefully someone can help me out with an issue I'm having with my 2004 Dodge 5.9L Cummins, 48RE tranny...i'm not throwing any codes but I do know that i'm having issues with low line pressure...its at about 60psi, its desired to be at 127-130psi & have no torque converter lockup...around 50-55mph it shifts back & forth from 3rd to 4th...if I get on it, it will go into 4th but as soon as I let off it shifts back into 3rd again....any ideas!?!

 

Sounds like a shot TQ lock up soleniod, or VB! Take it to a AAMCO or reputable tranny shop!