[Tyler11k]

So today, I bought a used 2009 volvo s40 1.6 diesel. Car seemed perfect when I drove it. No warning lights or anything. About an hour and a half into my journey home the red warning triangle popped up in the middle of the dash saying "Engine Mangment service urgent". Car seemed very dead. Any bit of an incline and the the car struggling. Long story short, the guy who sold me the car wasnt taking any responsibility. Pulled in and turned off the car and started it again. The warning light was still there and the car was going up through the gears fine but still seemed abit dead, once I hit 5th gear the car struggled to go above 115kmh. Once I got off the motorway and into the city it seemed alot better but all of a sudden it would seem dead again. Car is idling fine, no weird noises or clunks. Can anyone help please