I just test drove a 1990 4 matic wagon with 225M miles. Body was perfect, interior clean. Started fine. Acceleration is a bit sluggish, but my present car, a 1997 volvo T5 is very fast, so most cars seems sluggish in comparison. Ride was good, brakes good. However, the yellow 4-matic indicator on the dashboard was lit the whole time I drove it. Is this the sign of trouble?