97 Century major loss of power/hesitation under load

I own a 1997 Century 3100 V-6 132,000mi. recently i had noticed the speedometer was acting funny needle jumping about a 30 mph variance.the same day i noticed a slight studder, mostly noticeable on the freeway, as the problem progressed, the speedo stays at about 20 on the freeway, and now is undrivable as the last time i had it on the road it seems to have engine power and was just hi-reving like going into passing gear with even pressure on the pedal, not moving fast. let me know

You have a Vehicle Speed Sensor (VSS) located at the passenger side of the transaxle housing. It feeds voltage to the speedometer and the PCM module to control the transmission like shifting. It could be flaky or maybe there is a wiring or connector problem at the VSS since it is exposed to the elements.