I have a SAAB 9-3 Aero that stalls many times during a 12 mile trip to work. It has no rhyme nor reason. Could be stopped at an intersection or driving 50 mPH. One stopped on the road, I can remove the negative cable then replace it (the whole thing taking about 30 seconds and it starts back up and away we go for the next few miles, maybe 2 maybe 25. Any suggestions