I have a 98 chassis but everything else is a 1999 Dodge Diesel turbo Cummings when the engine gets started in the mornings, the transmission has trouble slipping into gear and staying there. Then once it is warmed up the OD slips in and out going down the road. I have replaced the computer, transmission relay, and the speed sensor. What else do I need to do to get this to work better.

 

Find out why it is doing it..... then fix it.

Could be any of a number of things, from bad sensors/solenoids in the trans, to a bad TPS. Test the easy stuff first, then go after the more interesting parts.