Transmission and speedometer work erratically

I have a 99 Dodge Ram 1500 4x4 Quad cab Sport. Sometimes speedo will work over 20MPH, and trans will shift fine. Other times speedo not working and trans will not upshift correctly, unless I put in neutral, let off RPM, and put back into drive then it will upshift manually. Other times will not work at all and other times works correctly right from take off. I have replaced speed sensor on the side of trans and rear axle ABS sensor, same problem still exists. Any assistance or feedback would be a big help, thanks! Jim

sounds like the pcm is going bad.

Thanks. I'll see if I can swap pcm with my 1998 if it is the same. I don't know if it is. I am going to pull the cover to clean out and change 90w and inspect. I will keep updating till it is fixed. Thanks for any other help on this matter, Jim