I have a 2005 Ram 2500 diesel with a 48re transmission I have replaced the torque converter that locked up I have replaced the throttle valve actuator I have replaced the governor pressure solenoid and transducer or pressure sensor whichever you want to call it I still have issues shifting I cannot grab first gear from Drive when I start I have to shift to neutral and back down to First manually to get first gear I don't know what else to do can anybody please help me

 

What is the mileage on your rig? Any mods? you might just be putting "band aids" on a bigger problem...….
For starters, clean all "ground" connections, as well wiring connectors for the trans. A bad ground can raise havoc, and create headaches.