this may not do nothing but the tansmission vacuum modulator could be the culprit for your shifting problem, costs about 20 bucks from autozone, not to hard to replace, i dont know if your vehicle has one, but im pretty sure it does. i think it might help with your shifting, as for speedometer you might just want to try a transmission shop, i believe the speed sensor goes from the end of the transmission, but that could get costly. I dont know a lot about trannys but i hope this at least helps somehow