well usually when the needle jumps like crazy diff speed, it means the sensor is lose and needs to b tight a 2seconds job.
The D4 light comes on within a few minutes and the Check Engine light will come <--- now thats a big problem sounds like it at least, take it to the shop run the code see whats wrong and d4 light going on is never good news either. i think autozone runs the code for free, the shop will charge $15. the needle jumping and D4 light going on i think that has to do with the transmission & sensorsso take it to a transmission place. maybe someone with more experience than i can add some facts.