I should have posted this reply here, instead of as a new thread:

I have a 89 300TE with 155k miles, trans replaced at 100k with rebuilt (not by dealer). I bought the vehicle 18 months ago, and have had no troubles (with the tranny anyway) until recently. Last week I started noticing a slight delay as the car shifted from 3-4. Now it's more noticeable, although not always consistent, and I'm begining to feel it in 2-3. I changed the fluid two days ago, everything appeared normal- no discoloration or material in the pan. My next step is to take it to a transmission expert, since I'm an hour away from the nearest MB dealer. Any thoughts or recommendations would be much appreciated.