I have a 91 420sel. It will drive fine and then it will just loose all power. It will kick in again and drive fine again for a few miles and then just loose all its power. some times it will loose power all the way till I stop and just die. Then I will start it and will die again. After a few times of trying to start it, it will stay started and will drive fine for a few more miles and will do the same thing again. Please help!!!!!!