'03 s40 with 95000 miles. after driving extended period of time, radio fades out, srs light comes on, dash board lights will either flicker or go out and the engine will shudder like its going to die but it doesnt this all happens in a 15-20 second time period. repair shop cant find anything wrong! of course it wont do it for them. it is now in for the second time. any ideas? please ???