That model has a kick down cut out relay module, which uses the tach and vehicle speed sensor as the input signal, to control engine speed in the kick down mode.

If the engine rpms should ever exceed its red line rpm limit in kick down mode, the relay module will interrupt power flow to the KD solenoid, allowing the transmission to up shift to a higher gear( kick down is a down shift to a lower gear) thus reducing the engines rpm. The cause can also be a in the up shift delay valves




You should first check for any codes that may be stored.