Dash Wiring problems of the 2000 Volvo C70

Car began shaking when driving. Pulled over to check the tires and did not observe a flat. When I restarted the car and pulled away from the curb, the car would not accelerate but the radio and lights from the dash were still operational. Power steering no longer worked as well. Car was towed to dealership. The throttle was replaced but the car continues to shake when accelerating but does not shut off. Have taken car to another mechanic but no error codes have been detected. Car is still unreliable.