I have 2003 3.9 liter automatic transmission Dakota with 159k miles on it. The only major work I’ve had done on it is I had to replace the PCM but had to get an aftermarket one flashed to my specs because the dealership wouldn’t do it because it was too old and that was done over 6-8 months ago. Recently in the past few weeks my truck has had trouble shifting while going under 40 mph. While driving I get up to about 20mph and my truck will start to over rev and then it gives a little jerk then shifts gears and then when I get to about 40mph it does this again but it will rev over 4K rpms and then it will jerk really hard and shift passed 40mph after like 3-5 seconds. A couple days ago I drained and changed the transmission fluid and filter and it seemed to help a little bit and it doesn’t jerk or stall as hard in the lower gears but still has a hard time shifting when I get to 40mph. Once I get passed 40mph the truck runs fine and shifts completely fine as I speed up but when I slow back down it has a rough time getting up passed 40 again. Any advice on what I should try or do next would be much appreciated! I don’t believe it’s the PCM but I did hear that it could be the truck isn’t registering that it’s a new gear but don’t know If that is accurate.

 

Welcome to DF!

Should have adjusted the bands in the trans when you changed the fluid/filter. Sounds like they are rather loose.... (which would explain your delayed shifts.)