1998 Chevy Malibu Car maintains speed without touching gas

While driving the past few days my malibu has kept driiving speeds of 55 mph to 65 mph without me touching the gas pedal or without using the cruise control. It is actually somewhat scarry as the car was difficult to stop. I would let off the gas and the car would just maintain 55-60 MPH on the highway for miles! When I would apply the brakes it would just go back up in speed and maintain it. To stop I actually had to pump the brakes a lot to get it to slow down. Then the RPM's kept upwards of 1,000-1,500+ when at a complete stop with my foot on the brake. Is this a throttle sticking issue or some type of computer control problem? Or is it an issue with the cruise control going crazy? Please help! Any suggestions would be greatly appreciated.
Thanks,
Jeremy