Hi folks. Anyone got any ideas about this?

My A3 170 is driving me mad. Sometimes it drives fantastic like it should, loads of torque and very responsive and other times it seems very flat in comparison. When it's driving properly I also notice the MPG predictor in the information panel is up around 47/48 around town but when it's flat it's down around 30. The odd thing is it seems to drive better later in the evening when the air temperature is slightly cooler. Yesterday I went out early afternoon and it was flying then parked up for 10 minutes, started it up again and it was flatter. It idles perfectly at exactly 800rpm and starts first turn of the key. Another thing to add is I get a strong smell of spent diesel most of the time and sometimes in the cabin. I don't think it's overfueling as there's no smoke whatsoever coming from the exhaust so


I'm thinking along the lines of either a fuel or oxygen blockage somewhere or even a leak. Could it be a sticky EGR or intake flap (throttle body)?


I'm puzzled!