I have a W123 300D-T with 200K miles on it, and all of the sudden, it seems to be really slow, and shifts really quickly. like before I even get to 30 mph, it has shifted all the way into 4th gear. I stomp on the gas and it will downshift but only for 1 second, then upshift again. This sounds like an expensive fix... Can anyone tell me what's wrong, and what needs to be done? $?
Darrell