ASSuming everything in the shift kit was installed correctly, you really need to hook a scan tool to it and monitor the target governor pressure vs actual governor pressure. With the key on/engine off monitor he actual governor pressure it should be reading zero. If it is reading some sort of pressure the governor pressure sensor/transducer is bad. If not, start and drive the truck. Monitor the governor pressure while taking off from a stop it should read closely to the speed you are going, i.e. 10 psi = 10 mph. It should do this until it goes into overdrive and lockup and then the pressure will spike to well over 100 psi. Pay special attention to the gov. pressure when coming to a stop. It should drop to zero. If it does not there is an issue with the governor pressure solenoid. If I were to guess, I would say you need a governor pressure solenoid. It is very common RE transmissions. Do you self a favor and buy a MOPAR one. I personnaly have had bad luck with the aftermarket units.