ASR/BAS light comes on - engine behaves erratically
 

Hi, i just got this wierd problem yesterday,
i have a 98' SLK200 and as i was driving it suddently started to jerk with the throttle and the ASR/BAS light came on. It stopped responding to the throttle and the car was shaking and i could hear that the engine was misfiring.
I managed to stop on a safe spot, turn the car off and then on again, and it was fine. I parked the car about three hours, when i turned the car on, it was all fine, but after about 10 minutes of driving i could feel that it was starting to go nuts again, random throttle peaks (like as if i pushed the pedal to the max for a split second), and then the throttle response dissapeared and the light came on again. I parked the car, turned it off and then on again, but then the light came on immediately and the car just revved up by it self for a second just when i started it (i didn't push the throttle). I popped the hood and the engine was shaking and misfiring, idling around 1100 rpm, no throttle response at all.
I believe it is something with the ASR since it can controll the throttle and cut ignition (i think).

Could anyone tell me what i should try to do before taking it to a service station (which will probably cost some major coin, as usual)?

Thanks!