OD Delayed Engage / Slippage?
 

1993 190e with 1987 motor and transmission. It shifts up fine until the final gear, at which point the RPMs rise like it is in neutral for maybe a second or two and then it engages the final gear. It is like you are leaving the throttle down on a stick shift as you change into the next gear. Again only when shifting into OD. If you leave it in 3rd it is fine but when you put it into D it does it as it changes into the final gear.

If you have an automatic, there is no overdrive. How long have you owned the vehicle?

Sounds like a 3-4 shift flare. Can you post a video? Every cel phone today has a video camera built in, capture it with good sound.

There are a variety of reasons this occurs. First, verify the fluid is clean and full. Next most common is the modulator turned down so the 1-2 upshift is tolerable, resulting is low pressure on the 2-3 and 3-4.