I have owned this 1987 300sdl for about 3 weeks and 500 miles now. The mileage is 175000. In general I am very happy with performance. So far I have had the Trap oxidizer removed, changed the oil, changed the fuel filters twice, once before the diesel purge and once after. I have also cleaned all lines associated with the ALDA. Oh and changed the serpentine belt, courtesy lights, broken head unit and speakers and I know none of these last things are relevant. Anyway 60 mph and 2500 rpm seems to be a lousy speed. Below that I have decent power, 3000 RPM and above power is great. On a slight hill at 2500 it just will not accelerate. It just spews out black smoke and sits there. If I floor it the car will downshift and take off fairly well. If I hit the same hill at 70 MPH the car will pull the hill easily at half throttle. All of this would not be a problem if I lived somewhere else but around here almost all of the speed limits are 55.