When I got mine, it was down on power but what did I know? And it shifted a bit weird...huh. Well, it's a Diesel and they're peculiar, right?
Uh, wrong. It's a modern MBZ Diesel, and it may be down on power but not finesse. Turns out it wasn't getting any turbo boost because of a simple vacuum leak, so Bam it now has adequate power and can accelerate up a hill
Once my car went under the knife (and I spent a grand), it now runs like it should, no excuses.
Get it checked by someone you trust