A broken kickdown cable typically causes issues with a car's upshifts, which are delayed or occur at full throttle. However, a faulty kickdown cable may only stick when the car in not in motion and cause no obvious symptoms during normal driving.
A kickdown cable that is not correctly adjusted may display some of the same symptoms as one that is faulty, but it can also cause the transmission to shift too early or not at all. In some cases, the cable itself may not be faulty. Instead, damage to the kickdown cable's housing can cause upshift problems, as can a faulty or misaligned throttle assembly or throttle spring.