I have an 85 300SD with about 300k miles on it. The poor old car is slower than dirt. 0-60 times are in the days. I have checked the boost ALDL etc. The car will smoke when floored so I know it is getting fuel, and since the boost pressure is high I was assuming it was getting air. However I recently thought about the intake being plugged with carbon. Is the 617 known for this? I don't think the intake has ever been off on the car.
BTW I just purchased a 560SEL to replace the 300SD but with gas prices lately it may be a bad idea. Trampas