Desperately running out of ideas with my 1999 A4 1.8se, Problem started after it was jump started battery to battery, - starts every turn of key, and if i floor it whilst starting will run immediately up to 2500 to 4000rpm without hesitation, but then dies to 600rpm before cutting out. Staring without flooring it will start at tickover speed - 900 to 1200 rpm, run for 30 seconds, drop to 600rpm and cut out. Replaced ecu with correctly coded immobiliser, and VAG COM shows no faults.

hope that someone may have an new idea to try, throttle body reset, all air intake pipes checked, plugs replaced, nothing made any difference whatsoever...willing to try anything including a personal breakdown!