I have a 2000 Dodge dakota sport 4x4 3.9l with automatic transmission. This truck has 107,000 miles currently and is all stock. 

    The problem I'm having (which I've come to learn is common on these models) is my transmission will not shift from 2nd to 3rd gear when I drive the truck after its been sitting overnight. I can start it up and take off and it's fine until I hit around 30mph and the rpms will just continue to rise while pressing on the accelerator without gaining anymore speed. If I let of the gas pedal and let the rpms come back down and then press on the gas again it will finally shift hard enough to jerk my body forward.  Sometimes it takes doing this several times before it will shift. 

  I would just get rid of the truck but it has sentimental value to me and for that reason I've decided to fix the issue. I would like to know what are my best options for getting this issue fixed. I'm afraid that if I simply get another transmission from a junk yard I'll have the same issue down the road. 

                                                Thank you