last night after going to shop I started car and it started really quick and was over running for 10 seconds then there were some strange rattling noises while driving home, Had a look under bonnet looked everywhere and nothing, Tried to start it again and nothing happened just a clunk, tried starting again and it started ok revved up all ok. My driveway is a big slop so I drove car down and reversed up just in case in the morning it did not start. This morning I started it no problem went to put it in gear I it just would not go in any gear while the engine was running. With engine off it went in every gear. So on my slop I started it in first gear, it started and jerked and cut out but then once restarted I had all gears working again. I drove the car fine in to town and parked. Came back started it and again no gears when engine running SO I DID THE SAME AS BEFORE STARTED IT IN GEAR, It worked again and drove home ... Any ideas guy's..

the car is an Audi 1.9tdi Avant estate 1997