I have a 1988 Buick LeSabre that has been pretty reliable up until recently. What is happening is when driving, particularly on the highway, the engine will just immediately shut off. When this happens, the "Check Engine" light, battery light, well all the warning light come on, but the engine is dead. Once you pull over you can start the car again with no problem, however, it will shut off again a few minutes later. This keeps happening in spurts, like it will happen for a day, then be fine for 2 days, then happen again. We had a new water pump and starter put in recently, but the mechanic can not seem to figure out what the problem with it is, and I don't want to do the old trial and error paying for repairs method. Is this a common issue?