What cause loss power on hills, over rev's when accelerated too fast and on hill on 2006 Ford Escape

Up hill, lose power and slow down by 20 kms. High RPM's when accelerating fast but can bring down if I let up on accelerator a bit as if I'm driving a standard without a clutch. WAY over rev's by its self uphill sometimes and I have to take it easy and let it off a bit to bring the RPM's down. Can not use cruise control because it over rev's to try to stay at speed up hills.

Asked by for the 2006 Ford Escape
Transmission is slipping!! Better get it looked ASAP!! May be too late 'now'....